Research Article Structural Behavior of Thin-Walled...
Transcript of Research Article Structural Behavior of Thin-Walled...
Research ArticleStructural Behavior of Thin-Walled Concrete-FilledSteel Tube Used in Cable Tunnel An Experimental andNumerical Investigation
Hetao Hou1 Su Ma1 Bing Qu12 Yanhong Liang1 Yanjun Jin3
Wencan Zhu1 and Lei Chen1
1School of Civil Engineering Shandong University Jinan 250061 China2Department of Civil and Environmental Engineering California Polytechnic State University San Luis Obispo CA 93407 USA3Department of Building Engineering Mianyang Vocational and Technical College Mianyang 621000 China
Correspondence should be addressed to Bing Qu bqucalpolyedu
Received 26 April 2015 Revised 9 June 2015 Accepted 10 June 2015
Academic Editor Robert Cerny
Copyright copy 2015 Hetao Hou et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
One steel grid and five thin-walled concrete-filled steel tubes (CTST) used as the supports of tunnel were tested in site forinvestigating the mechanical behavior The mechanical influences of thickness node form and concrete on CTST were gainedand compared with the impacts on steel grid It is indicated that high antideformation capacity of CTST improved the stability ofsurrounding rock in short time The cementitious grouted sleeve connection exhibited superior flexibility when CTST was erectedand built Although the deformation of rock and soil in the tunnel was increasing good compression resistance was observedby CTST with the new connection type It was also seen that vault tube foot and connections were with larger absolute strainvalues The finite element analysis (FEA) was carried out using ABAQUS program The results were validated by comparison withexperimental results The FE model could be referred by similar projects
1 Introduction
Although steel grid and steel arch are common used struc-tures for tunnel support they are not good enough forlarge deformation control of soft rock As a new structureconcrete-filled steel tubes (CFST) with high bearing capacityand good plasticity have a broad application prospect [1ndash3] Under compressive loading the local buckling resistanceof the steel tube could be effectively enhanced by the filledconcrete At the same time the strength plasticity andtoughness of the concrete can also be boosted [4] Li etal [5] pointed out that deformation of surrounding rockcould be effectively reduced byCFST for roadway supportingHowever the cost of CFST has to be reduced
Compared with ordinary CFST less steel and weldingwork are needed for CTST because of the thin wall Previousresearch mainly focused on the experimental behaviour ofCTST in the laboratory [6ndash8] Despite low cost few studies
are conducted in site to test the influences of wall thicknessand mechanical properties
In this study tests have been done in a cable tunnel inJinan while an FE analysis by ABAQUS program is con-ducted to do further research on the application of CTST intunnel
2 Test program
21 Project Background of Cable Tunnel The cable tunnel islocated in Shunhua Road in Jinan As the tunnel in strongweathered rock it is 145m long The thickness of overlayingsoil of the tunnel is about 67sim8mThemaximum excavationheight is 46m while the largest excavation span is 675mFor presupport advanced small pipes with 15m longitudinaldistance are supplementedThenC25 early-strength concreteis sprayed for primary support Subsequently steel grid orCTST is used to support the tunnel At last C30 waterproof
Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2015 Article ID 781823 12 pageshttpdxdoiorg1011552015781823
2 Advances in Materials Science and Engineering
Table 1 Parameters of CTST specimens
Specimens ST-1 ST-2 ST-3 ST-4 ST-5119863 (mm) 159 159 159 159 159119905 (mm) 55 45 35 55 55Concrete Filled in Filled in Filled in Not filled in Filled in
Connection Cementitiousgrouted sleeve
Cementitiousgrouted sleeve
Cementitiousgrouted sleeve
Cementitiousgrouted sleeve Ordinary sleeve
Note119863 is the external diameter and 119905 is the thickness
2139
2245
3900
484
1627
1627
6750
Connection 2
Connection 1
484
1942
1942
1089 10892409
L3
R1421
R8293
L3
L2 L2
L1
120601159 times 35(45ndash55)
Figure 1 Size and segmentation of CTST support
concrete with seepage resistance 119875 gt 8 is adopted to improvethe secondary lining
22 Test Specimen In the study the steel tube is segmentedfor installation and transport One end of segment is sealedwhile the other is opened The segment is sealed by precasthead pale once the concrete vibrating finished Finally thesegments are spliced in site According to the results ofgeological exploration the counter-arch for the support isnot set owing to the small effect of soil arch The size andsegmentation of CTST support are shown in Figure 1
5 CTST specimens and 1 steel grid specimen are testedThe details of the test specimens are shown in Figure 2 andTable 1
For the butt joint in the tunnel a new cementitiousgrouted sleeve connection is designed and shown in Figure 3Microexpansive cement mortar is grouted after the con-nection inserting Comparing with the traditional connec-tion the new type with better yielding could satisfy therequirements of surrounding rock pressure Besides the newconnection could reduce the welding works and avoid thetunnel excavation generated by butt joints
According to ldquometallic materials at ambient temperaturetensile test methodrdquo (GBT228-2002) steel tube Q235B isused in the test The yield strength of the steel tube is2553MPa while the tensile strength is 3307MPaThe elasticmodulus is 206 times 105MPa and Poissonrsquos ratio is 030 As whatis shown in Figure 4 the steel tube is bent into the designed
270
270
112060125
112060125
212060125
12060114300
12060114300
12060114300
Figure 2 Steel grid section
Head pale 1
230
20
70
5050 26
0
70
704
CTST
Micro-expansivecement mortar
70
120601159 times 80mm
Rubber mat
120601140 times 20mmHead pale 2120601108 times 80mm
t = 8mm
12060116 hale
12060116 hale
M14
M14
Figure 3 Details of cementitious grouted sleeve connection
shape in the factory and then is stereotyped under cryogeniccooling
The mix proportion of cement sand and gravel usedin the concrete is 1 151 245 The water cement ratio ofthe cement is 041 The expansion agent ratio is 11 Thewater reducing agent ratio is 05 According to the relevant
Advances in Materials Science and Engineering 3
Figure 4 Manufacturing procedure of steel tube in factory
Figure 5 Material test of concrete
Table 2 Compressive strength of concrete at different ages
Age 3 d 7 d 28 dCompressive strength (MPa) 163 248 455
Chinese standards compression tests are carried out asshown in Figure 5 and Table 2 The elastic modulus (Ec) is316 times 104MPa
3 Test Monitoring and Analysis
31 Test Monitoring Program
311 Displacement Monitoring Vault and convergency dis-placement are monitored in the test The settlement value istested with a level and the convergency values are tested witha convergence device
312 Strain Monitoring It is shown in Figure 6 that theresistance strain gauge and fiber are set only on one side of thespecimen for symmetryMeasuring point arrangement can bedivided into the vault area (C1 A1 and S1) the largest cornerarea (C2 S2) the top of the straight wall area (S3 B1) thestraight wall area (A2) and the connection area (from D1 toD4) in which S1simS3 are fiber grating measuring points
313 Pressure Monitoring As what is shown in Figures 7and 8 three pressure gauges (Y1simY3) are set between CTST
1000
A2
D3
D1
D2
D4
B1S3
S2C2
C1A1S1
Figure 6 The location of resistance strain gauge and fiber
1500
Y3
Y2
Y1
3072
Figure 7 The location of pressure gauge
support (or the steel grid support) and surrounding rockThe pressure gauges are tied to the designed position on theoutside surface of the support in site
32 Test Results Analysis
321 Displacement Monitoring Results Analysis The settle-ment-time curves in the vaults and convergency value-timecurves in both sides are shown in Figures 9 and 10 It isobserved that the biggest settlement in the vaults of CTSTwith concrete is less than 5mm while for the one withoutconcrete it is less than 75mm The steel gridrsquos biggestsettlement in the vaults is less than 7mmAll the convergencyvalues in both sides of the supports are less than 18mmThevertical and horizontal deformations of the tunnel are stableafter 10 days so the unobvious deformations in the latter arenot shown in Figure 9
Figures 11 and 12 present load-settlement curves in thevaults and load-convergency value curves in both sides
It is shown in Figure 11 that the curves of ST-1simST-3appeared under the concave due to connection scalability and
4 Advances in Materials Science and Engineering
(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ
Figure 8 Pressure measurement in situ
0 2Time (d)
4 6 8 10 12
1
2
3
4
5
6
7
8
ST-1ST-2ST-3
ST-4ST-5GS
Settl
emen
t (m
m)
Figure 9 Settlement-time curves in the vaults
0 2 4 6 8 10 12
02
04
06
08
10
12
14
16
18
Time (d)
Con
verg
ency
val
ue (m
m)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 10 Convergency value-time curves in both sides
Advances in Materials Science and Engineering 5
0 1 2 3 4 5 6 7 8
10
20
30
40
50
60
70
80
90
100
Settlement (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 11 Load-settlement curves in the vaults
02 04 06 08 10 12 14 160
10
20
30
40
50
60
70
80
90
100
Convergency value (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 12 Load-convergency value curves in both sides
smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents
that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged
It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness
6 Advances in Materials Science and Engineering
0 40 80 120 160 2000
5
10
15
20
25
30
35
40
45
50Lo
ad (k
Nm
)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) C1
4000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120
(b) C2
00
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120minus160minus200
(c) S3
Figure 13 Load-strain curves in the outer edge of the CTST supports
322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored
(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains
are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation
(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line
(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in
Advances in Materials Science and Engineering 7
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40minus60minus80minus100 minus20
ST-1ST-2ST-3
ST-4ST-5
(a) A1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200
ST-1ST-2ST-3
ST-4ST-5
(b) A2
Figure 14 Load-strain curves on the center axis of the CTST supports
the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously
(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576
(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18
It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger
4 Numerical Analysis
41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030
The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840
119888 1198911015840119888mean compression
cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model
Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19
In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results
42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
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2 Advances in Materials Science and Engineering
Table 1 Parameters of CTST specimens
Specimens ST-1 ST-2 ST-3 ST-4 ST-5119863 (mm) 159 159 159 159 159119905 (mm) 55 45 35 55 55Concrete Filled in Filled in Filled in Not filled in Filled in
Connection Cementitiousgrouted sleeve
Cementitiousgrouted sleeve
Cementitiousgrouted sleeve
Cementitiousgrouted sleeve Ordinary sleeve
Note119863 is the external diameter and 119905 is the thickness
2139
2245
3900
484
1627
1627
6750
Connection 2
Connection 1
484
1942
1942
1089 10892409
L3
R1421
R8293
L3
L2 L2
L1
120601159 times 35(45ndash55)
Figure 1 Size and segmentation of CTST support
concrete with seepage resistance 119875 gt 8 is adopted to improvethe secondary lining
22 Test Specimen In the study the steel tube is segmentedfor installation and transport One end of segment is sealedwhile the other is opened The segment is sealed by precasthead pale once the concrete vibrating finished Finally thesegments are spliced in site According to the results ofgeological exploration the counter-arch for the support isnot set owing to the small effect of soil arch The size andsegmentation of CTST support are shown in Figure 1
5 CTST specimens and 1 steel grid specimen are testedThe details of the test specimens are shown in Figure 2 andTable 1
For the butt joint in the tunnel a new cementitiousgrouted sleeve connection is designed and shown in Figure 3Microexpansive cement mortar is grouted after the con-nection inserting Comparing with the traditional connec-tion the new type with better yielding could satisfy therequirements of surrounding rock pressure Besides the newconnection could reduce the welding works and avoid thetunnel excavation generated by butt joints
According to ldquometallic materials at ambient temperaturetensile test methodrdquo (GBT228-2002) steel tube Q235B isused in the test The yield strength of the steel tube is2553MPa while the tensile strength is 3307MPaThe elasticmodulus is 206 times 105MPa and Poissonrsquos ratio is 030 As whatis shown in Figure 4 the steel tube is bent into the designed
270
270
112060125
112060125
212060125
12060114300
12060114300
12060114300
Figure 2 Steel grid section
Head pale 1
230
20
70
5050 26
0
70
704
CTST
Micro-expansivecement mortar
70
120601159 times 80mm
Rubber mat
120601140 times 20mmHead pale 2120601108 times 80mm
t = 8mm
12060116 hale
12060116 hale
M14
M14
Figure 3 Details of cementitious grouted sleeve connection
shape in the factory and then is stereotyped under cryogeniccooling
The mix proportion of cement sand and gravel usedin the concrete is 1 151 245 The water cement ratio ofthe cement is 041 The expansion agent ratio is 11 Thewater reducing agent ratio is 05 According to the relevant
Advances in Materials Science and Engineering 3
Figure 4 Manufacturing procedure of steel tube in factory
Figure 5 Material test of concrete
Table 2 Compressive strength of concrete at different ages
Age 3 d 7 d 28 dCompressive strength (MPa) 163 248 455
Chinese standards compression tests are carried out asshown in Figure 5 and Table 2 The elastic modulus (Ec) is316 times 104MPa
3 Test Monitoring and Analysis
31 Test Monitoring Program
311 Displacement Monitoring Vault and convergency dis-placement are monitored in the test The settlement value istested with a level and the convergency values are tested witha convergence device
312 Strain Monitoring It is shown in Figure 6 that theresistance strain gauge and fiber are set only on one side of thespecimen for symmetryMeasuring point arrangement can bedivided into the vault area (C1 A1 and S1) the largest cornerarea (C2 S2) the top of the straight wall area (S3 B1) thestraight wall area (A2) and the connection area (from D1 toD4) in which S1simS3 are fiber grating measuring points
313 Pressure Monitoring As what is shown in Figures 7and 8 three pressure gauges (Y1simY3) are set between CTST
1000
A2
D3
D1
D2
D4
B1S3
S2C2
C1A1S1
Figure 6 The location of resistance strain gauge and fiber
1500
Y3
Y2
Y1
3072
Figure 7 The location of pressure gauge
support (or the steel grid support) and surrounding rockThe pressure gauges are tied to the designed position on theoutside surface of the support in site
32 Test Results Analysis
321 Displacement Monitoring Results Analysis The settle-ment-time curves in the vaults and convergency value-timecurves in both sides are shown in Figures 9 and 10 It isobserved that the biggest settlement in the vaults of CTSTwith concrete is less than 5mm while for the one withoutconcrete it is less than 75mm The steel gridrsquos biggestsettlement in the vaults is less than 7mmAll the convergencyvalues in both sides of the supports are less than 18mmThevertical and horizontal deformations of the tunnel are stableafter 10 days so the unobvious deformations in the latter arenot shown in Figure 9
Figures 11 and 12 present load-settlement curves in thevaults and load-convergency value curves in both sides
It is shown in Figure 11 that the curves of ST-1simST-3appeared under the concave due to connection scalability and
4 Advances in Materials Science and Engineering
(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ
Figure 8 Pressure measurement in situ
0 2Time (d)
4 6 8 10 12
1
2
3
4
5
6
7
8
ST-1ST-2ST-3
ST-4ST-5GS
Settl
emen
t (m
m)
Figure 9 Settlement-time curves in the vaults
0 2 4 6 8 10 12
02
04
06
08
10
12
14
16
18
Time (d)
Con
verg
ency
val
ue (m
m)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 10 Convergency value-time curves in both sides
Advances in Materials Science and Engineering 5
0 1 2 3 4 5 6 7 8
10
20
30
40
50
60
70
80
90
100
Settlement (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 11 Load-settlement curves in the vaults
02 04 06 08 10 12 14 160
10
20
30
40
50
60
70
80
90
100
Convergency value (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 12 Load-convergency value curves in both sides
smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents
that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged
It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness
6 Advances in Materials Science and Engineering
0 40 80 120 160 2000
5
10
15
20
25
30
35
40
45
50Lo
ad (k
Nm
)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) C1
4000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120
(b) C2
00
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120minus160minus200
(c) S3
Figure 13 Load-strain curves in the outer edge of the CTST supports
322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored
(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains
are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation
(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line
(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in
Advances in Materials Science and Engineering 7
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40minus60minus80minus100 minus20
ST-1ST-2ST-3
ST-4ST-5
(a) A1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200
ST-1ST-2ST-3
ST-4ST-5
(b) A2
Figure 14 Load-strain curves on the center axis of the CTST supports
the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously
(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576
(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18
It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger
4 Numerical Analysis
41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030
The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840
119888 1198911015840119888mean compression
cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model
Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19
In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results
42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
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Biomaterials
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NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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CrystallographyJournal of
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Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 3
Figure 4 Manufacturing procedure of steel tube in factory
Figure 5 Material test of concrete
Table 2 Compressive strength of concrete at different ages
Age 3 d 7 d 28 dCompressive strength (MPa) 163 248 455
Chinese standards compression tests are carried out asshown in Figure 5 and Table 2 The elastic modulus (Ec) is316 times 104MPa
3 Test Monitoring and Analysis
31 Test Monitoring Program
311 Displacement Monitoring Vault and convergency dis-placement are monitored in the test The settlement value istested with a level and the convergency values are tested witha convergence device
312 Strain Monitoring It is shown in Figure 6 that theresistance strain gauge and fiber are set only on one side of thespecimen for symmetryMeasuring point arrangement can bedivided into the vault area (C1 A1 and S1) the largest cornerarea (C2 S2) the top of the straight wall area (S3 B1) thestraight wall area (A2) and the connection area (from D1 toD4) in which S1simS3 are fiber grating measuring points
313 Pressure Monitoring As what is shown in Figures 7and 8 three pressure gauges (Y1simY3) are set between CTST
1000
A2
D3
D1
D2
D4
B1S3
S2C2
C1A1S1
Figure 6 The location of resistance strain gauge and fiber
1500
Y3
Y2
Y1
3072
Figure 7 The location of pressure gauge
support (or the steel grid support) and surrounding rockThe pressure gauges are tied to the designed position on theoutside surface of the support in site
32 Test Results Analysis
321 Displacement Monitoring Results Analysis The settle-ment-time curves in the vaults and convergency value-timecurves in both sides are shown in Figures 9 and 10 It isobserved that the biggest settlement in the vaults of CTSTwith concrete is less than 5mm while for the one withoutconcrete it is less than 75mm The steel gridrsquos biggestsettlement in the vaults is less than 7mmAll the convergencyvalues in both sides of the supports are less than 18mmThevertical and horizontal deformations of the tunnel are stableafter 10 days so the unobvious deformations in the latter arenot shown in Figure 9
Figures 11 and 12 present load-settlement curves in thevaults and load-convergency value curves in both sides
It is shown in Figure 11 that the curves of ST-1simST-3appeared under the concave due to connection scalability and
4 Advances in Materials Science and Engineering
(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ
Figure 8 Pressure measurement in situ
0 2Time (d)
4 6 8 10 12
1
2
3
4
5
6
7
8
ST-1ST-2ST-3
ST-4ST-5GS
Settl
emen
t (m
m)
Figure 9 Settlement-time curves in the vaults
0 2 4 6 8 10 12
02
04
06
08
10
12
14
16
18
Time (d)
Con
verg
ency
val
ue (m
m)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 10 Convergency value-time curves in both sides
Advances in Materials Science and Engineering 5
0 1 2 3 4 5 6 7 8
10
20
30
40
50
60
70
80
90
100
Settlement (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 11 Load-settlement curves in the vaults
02 04 06 08 10 12 14 160
10
20
30
40
50
60
70
80
90
100
Convergency value (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 12 Load-convergency value curves in both sides
smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents
that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged
It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness
6 Advances in Materials Science and Engineering
0 40 80 120 160 2000
5
10
15
20
25
30
35
40
45
50Lo
ad (k
Nm
)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) C1
4000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120
(b) C2
00
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120minus160minus200
(c) S3
Figure 13 Load-strain curves in the outer edge of the CTST supports
322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored
(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains
are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation
(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line
(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in
Advances in Materials Science and Engineering 7
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40minus60minus80minus100 minus20
ST-1ST-2ST-3
ST-4ST-5
(a) A1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200
ST-1ST-2ST-3
ST-4ST-5
(b) A2
Figure 14 Load-strain curves on the center axis of the CTST supports
the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously
(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576
(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18
It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger
4 Numerical Analysis
41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030
The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840
119888 1198911015840119888mean compression
cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model
Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19
In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results
42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
4 Advances in Materials Science and Engineering
(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ
Figure 8 Pressure measurement in situ
0 2Time (d)
4 6 8 10 12
1
2
3
4
5
6
7
8
ST-1ST-2ST-3
ST-4ST-5GS
Settl
emen
t (m
m)
Figure 9 Settlement-time curves in the vaults
0 2 4 6 8 10 12
02
04
06
08
10
12
14
16
18
Time (d)
Con
verg
ency
val
ue (m
m)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 10 Convergency value-time curves in both sides
Advances in Materials Science and Engineering 5
0 1 2 3 4 5 6 7 8
10
20
30
40
50
60
70
80
90
100
Settlement (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 11 Load-settlement curves in the vaults
02 04 06 08 10 12 14 160
10
20
30
40
50
60
70
80
90
100
Convergency value (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 12 Load-convergency value curves in both sides
smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents
that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged
It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness
6 Advances in Materials Science and Engineering
0 40 80 120 160 2000
5
10
15
20
25
30
35
40
45
50Lo
ad (k
Nm
)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) C1
4000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120
(b) C2
00
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120minus160minus200
(c) S3
Figure 13 Load-strain curves in the outer edge of the CTST supports
322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored
(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains
are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation
(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line
(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in
Advances in Materials Science and Engineering 7
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40minus60minus80minus100 minus20
ST-1ST-2ST-3
ST-4ST-5
(a) A1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200
ST-1ST-2ST-3
ST-4ST-5
(b) A2
Figure 14 Load-strain curves on the center axis of the CTST supports
the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously
(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576
(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18
It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger
4 Numerical Analysis
41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030
The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840
119888 1198911015840119888mean compression
cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model
Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19
In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results
42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 5
0 1 2 3 4 5 6 7 8
10
20
30
40
50
60
70
80
90
100
Settlement (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 11 Load-settlement curves in the vaults
02 04 06 08 10 12 14 160
10
20
30
40
50
60
70
80
90
100
Convergency value (mm)
Load
(kN
)
ST-1ST-2ST-3
ST-4ST-5GS
Figure 12 Load-convergency value curves in both sides
smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents
that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged
It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness
6 Advances in Materials Science and Engineering
0 40 80 120 160 2000
5
10
15
20
25
30
35
40
45
50Lo
ad (k
Nm
)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) C1
4000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120
(b) C2
00
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120minus160minus200
(c) S3
Figure 13 Load-strain curves in the outer edge of the CTST supports
322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored
(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains
are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation
(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line
(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in
Advances in Materials Science and Engineering 7
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40minus60minus80minus100 minus20
ST-1ST-2ST-3
ST-4ST-5
(a) A1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200
ST-1ST-2ST-3
ST-4ST-5
(b) A2
Figure 14 Load-strain curves on the center axis of the CTST supports
the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously
(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576
(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18
It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger
4 Numerical Analysis
41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030
The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840
119888 1198911015840119888mean compression
cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model
Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19
In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results
42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
6 Advances in Materials Science and Engineering
0 40 80 120 160 2000
5
10
15
20
25
30
35
40
45
50Lo
ad (k
Nm
)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) C1
4000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120
(b) C2
00
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
minus40minus80minus120minus160minus200
(c) S3
Figure 13 Load-strain curves in the outer edge of the CTST supports
322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored
(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains
are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation
(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line
(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in
Advances in Materials Science and Engineering 7
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40minus60minus80minus100 minus20
ST-1ST-2ST-3
ST-4ST-5
(a) A1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200
ST-1ST-2ST-3
ST-4ST-5
(b) A2
Figure 14 Load-strain curves on the center axis of the CTST supports
the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously
(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576
(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18
It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger
4 Numerical Analysis
41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030
The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840
119888 1198911015840119888mean compression
cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model
Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19
In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results
42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 7
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40minus60minus80minus100 minus20
ST-1ST-2ST-3
ST-4ST-5
(a) A1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200
ST-1ST-2ST-3
ST-4ST-5
(b) A2
Figure 14 Load-strain curves on the center axis of the CTST supports
the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously
(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576
(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18
It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger
4 Numerical Analysis
41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030
The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840
119888 1198911015840119888mean compression
cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model
Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19
In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results
42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
8 Advances in Materials Science and Engineering
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275
ST-1ST-2ST-3
ST-4ST-5
(a) S1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(b) S2
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
0(120583120576)
minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250
ST-1ST-2ST-3
ST-4ST-5
(c) B1
Figure 15 Load-strain curves in the inner edge of the CTST supports
From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable
which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects
5 Conclusions
In line with the results of the experimental study and FEAanalysis the results could be summarized as follows
(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 9
0 50 100 150 2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
(a) D1
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus200minus250
(b) D2
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus2000
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(c) D3
0
5
10
15
20
25
30
35
40
45
50
Load
(kN
m)
(120583120576)
ST-1ST-2ST-3
ST-4ST-5
0minus50minus100minus150minus250 minus200
(d) D4
Figure 16 Load-strain curves at the connections of the CTST supports
ST-1 ST-2 ST-3 ST-4 ST-5
1172 1242 1284 1313 2003 18521795 17621758 1797
minus1229 minus929 minus1253 minus1412minus1463
minus1974minus1885
minus963
minus1905minus1873
minus1062
minus1995minus1942
minus1037
minus1495minus145
minus663
minus1795minus175
minus97
Figure 17 Strain distribution curves in the outer edge of the CTST supports
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
10 Advances in Materials Science and Engineering
ST-1 ST-2 ST-3 ST-4 ST-5
minus2134 minus1645 minus2175 minus2237 minus2361
minus2302minus2285
minus2315
minus2465 minus238
minus1796minus1555
minus1935
minus2059 minus2503
minus1964
minus1499
minus1758
minus1883minus2243
minus1396
minus1094
minus1285
minus1785minus192
minus2095
minus1562
minus1881
minus1956 minus2408
Figure 18 Strain distribution curves in the inner edge of the CTST supports
(a) The whole mesh of tunnel
X
Y
Z
(b) Lining and supportmesh
Figure 19 Mesh of steel tube model
ST-1 ST-2 ST-3
1853 1348 1434
minus1337
minus1858
minus108
minus989
minus133
minus722
minus1354
minus1912
minus1034
Figure 20 Strain distribution curves in the outer edge of the CTST supports
ST-1 ST-2 ST-3
minus2303
minus1003
minus1479
minus1913 minus2473
minus1854
minus1447
minus2337minus1714
minus1474
minus2153
minus2527
Figure 21 Strain distribution curves in the inner edge of the CTST supports
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 11
Table3Com
paris
onof
them
axim
alstr
ainbetweenFE
Aandtestresults
Locatio
nSpecim
enST
-1ST
-2ST
-3120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100120576
119879120576
FEM(|120576
FEMminus120576
119879|120576
FEM)times100
Theo
uter
edge
Vault
1797
1853
30
1242
1348
79
1313
1434
84
Largestcorner
minus97minus108
102
minus663minus722
82
minus1037minus1034
30
Topof
thes
traightw
allminus175minus1858
58
minus145minus133
90
minus1942minus1912
16
Foot
minus1229minus1337
81
minus929minus989
61
minus1253minus1354
75
Theinn
eredge
Vault
minus2408minus2527
47
minus192minus1913
40
minus2243minus2473
93
Largestcornerminus1881minus2153
26
minus1285minus1479
13
minus1758minus1854
52
Topof
thes
traightw
allminus1562minus1474
60
minus1094minus1003
91
minus1499minus1447
36
Foot
minus2134minus2303
73
minus1645minus1714
40
minus2175minus2337
69
Note120576119879means
them
axim
umstr
ainvalueo
fexp
erim
entand120576FE
Mmeans
them
axim
umstr
ainvalueo
fFEM
Tensiles
trainispo
sitivecompressiv
estrainisnegativ
e
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
12 Advances in Materials Science and Engineering
(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained
(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation
(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger
(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects
Conflict of Interests
The authors declare that they have no conflict of interests
References
[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008
[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009
[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014
[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011
[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)
[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013
[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000
[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials