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Rajshahi University of Engineering & TechnologyDepartment of Civil Engineering

EXPERIMENTAL INVESTIGATION ON CONCRETE FILLED STEELTUBULAR COLUMN USING GS SHEET STRENGHTENED WITH

SELF-COMPACTING CONCRETE COLUMN.

SUPERVISED BY PRESENTED BY

Dr. Tarif Uddin Ahmed Al-Amin Bin AzizProfessor Roll no. 100018Department of Civil Engineering Moniruzzaman RubelRajshahi University of Engineering & Technology Roll no. 100093

Presentation OutlineIntroductionBackgroundApplicationObjectivesScope of workLaboratory InvestigationExperimental InvestigationConclusion

IntroductionRecently different types of composite material have been widely applied to concrete column to provide better performance of column system. Concrete-filled steel tube column system has turned out to be one of the most successful composite concrete column. The concrete-filled steel tubular column offers numerous structural benefits-

High strength, fire and corrosion resistances Favorable ductility and large energy absorption capacities There is also no need for the use of shuttering during concrete

construction Construction cost and time are reduced.

These advantages have been widely exploited and have led to the extensive use of concrete-filled tubular structures in civil engineering structures.

BackgroundBaoChun Chen in 2009, this paper briefly introduces the present situation of concrete filled steel tube arch bridges in China. More than 200 concrete filled steel tubular arch bridges were

investigated and analyzed.

Qing Quan Liang and Sam Fragomeni in 2009, Quin and Sam had presented accurate constitutive models for normal and high strength concrete confined by either normal or high

strength circular steel tubes.

Shankar Jagadesh in May 2014, Concrete-filled steel tubes are gaining increasing prominence in a variety of engineering structures. The study about the behavior and the

characteristics of concrete filled steel tubular columns is the prime need of the hour.

Most of the investigation have been conducted using cast iron steel column, carbon fiber reinforced polymer or other types of steel columns of various shapes.

Experimental Investigation on GS sheet steel tube columns have been rarely used.

So we are investigating on CONCRETE FILLED STEEL TUBE USING GALVANIZING STEEL SHEET COLUMNS.

ApplicationConcrete filled steel tube structure are widely used.

Used in buildings to avoid having large size columns

In super high-rise structures like CANTON TOWER

Applied in many types of bridges such as arch bridges, cable bridges, suspension bridges and truss bridges.

Used in the construction and the upgrade of poles and transmission towers as well

Steel tube columns

Electric pole

Canton Tower, china

CFST used in bridges

Building frame construction

ObjectivesTo evaluate the Compression effect of concrete columns

strengthen by using the GS sheet materials.

To observe the behaviors of the confined and unconfined (self-compacted) concrete columns subjected to monotonic axial loading.

Evaluating the stress-strain & deflection curve for confined and unconfined specimens.

To obtain a concept about the variation of results from stress-strain curve.

Scope of WorkThis study discusses an experimental process in which

i. Short steel tube columns are taken under consideration to compare the strength variation with the normally casted self-compacted unconfined columns.

ii. The slenderness ratio of the column specimen was taken under consideration for the computation of strength

iii. Monotonic axial load was applied to the circular face of the columns.

iv. The benefits of the confinement effect were focused in the study by means of both experimental and analytical point of view.

Laboratory InvestigationLaboratory Investigation is divided into three different stages:i. Determination of physical properties of various material including specific gravity, BSG,

ACV, Compressive strength of cement, Fineness modulus etc.

ii. Preparation of steel tubular concrete columns and unconfined concrete columns were prepared in two mix proportions.

Concrete mix proportions

Series no. Proportion Confined

specimen

Unconfined

specimen

Water-Cement

Ratio

1 1 : 2 : 4 C1, C2, C3,

C4, C5, C6

U1, U2, U3 .51

2 1 : 1.5 : 3 C7, C8, C9,

C10, C11, C12

U4, U5, U6 .51

Illustration of preparing molds

Cutting of GS sheet. Rounding the steel sheet into circular shape

Welding the GS sheet columnTubular column after welding.

GS sheet tubular columns

Series no. Specimen no. Outer dia Φ

(cm)

Height (cm)

 

 1

U1 19.05  

60.96U2 13.97

U3 8.89

 

 2

U4 19.05  

60.96U5 13.97

U6 8.89

Series

no.

Specime

n no.

Outer

dia Φ

(cm)

Core

dia Φ

(cm)

Thickness

of steel columns

(cm)

Heightof

columns (cm)

 

1

C1 19.25 19.05 0.1 60.96

C2

C3 14.17 13.91 0.1 60.96

C4

C5 9.09 8.89 0.1 60.96

C6

 

 

 

2

C7 19.25 19.05 0.1 60.96

C8

C9 14.17 13.91 0.1 60.96

C10

C11 9.09 8.89 0.1 60.96

C12

Details of test specimen for Confined Columns & Unconfined columns

Casting of steel tubular columns after 24 hours.

Casting of unconfined columns after 24 hours

III. The specimens were tested in the appropriate set-up.

Test setup

Experimental InvestigationSerialNo.

Castingcriteria

Specimen

 

Crackingload(kN)

 

Ultimateload(kN)

 

Ultimate VerticalDeformation(mm)

 

   

01

Confined(1:2:4)

C1 592 608 3.048C2 427 448 3.239

C3 340 358 2.667

C4 325 349 3.747C5 195 216 2.858

C6 178 197 .9525Unconfined

(1:2:4)U1 295 322 3.302

U2 170 186 4.166U3 81 92 3.215

        

02

Confined(1:1.5:3)

C7 422 443 2.858C8 415 430 1.079

C9 285 302 3.429C10 347 368 3.683C11 219 235 2.261

C12 138 152 1.753Unconfined

(1:1.5:3)

U4 288 308 3.901U5 124 141 2.096

U6 43 66 2.136

0 0.1 0.2 0.3 0.4 0.5 0.60

5

10

15

20

25

C1Polynomial (C1)C7Polynomial (C7)U1Polynomial (U1)

STRAIN %

STR

ESS

(MPa

)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

5

10

15

20

25

C3Polynomial (C3)C9Polynomial (C9)U2Polynomial (U2)

STRAIN %

STR

ESS

(MPa

)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50

5

10

15

20

25

30

35

C6Polynomial (C6)C12Polynomial (C12)U3Polynomial (U3)

STRAIN %

STR

ESS

(MPa

)

SpecificationsC1-C6 confined (1:2:4)

C7-C12 confined (1:1.5:3)U1-U3 unconfined (1:2:4)

U4-U6 unconfined (1:1.5:3)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

5

10

15

20

25

C2Polynomial (C2)C8Polynomial (C8)U4Polynomial (U4)

STRAIN %

STR

ESS

(MPa

)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50

5

10

15

20

25

C10Polynomial (C10)C4Polynomial (C4)U5Polynomial (U5)

STRAIN %

STR

ESS

(MPa

)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50

5

10

15

20

25

30

35

C11Polynomial (C11)C5Polynomial (C5)U6Polynomial (U6)

STRAIN %

STR

ESS

(MPa

)

SpecificationsC1-C6 confined (1:2:4)

C7-C12 confined (1:1.5:3)U1-U3 unconfined (1:2:4)U4-U6 unconfined (1:1.5:3

FAILURE OF COLUMN SPECIMEN

Fails at top portion

Fails at mid portion

Fails at top

Failure zone

(bottom)Confined column Unconfined

columns

Conclusioni. The confined column has less axial deformation in comparison to the

unconfined column when subjected to same amount of load.

ii. The failure of the confined columns initiates from the development of deformation in steel sheet at top and bottom portion of the column, when the

ultimate load is applied the deformation initiates in the middle portion.

iii. In case of shear failure, the concrete encased fail first due to shear. In the second modes of failure there is a plastic deformation in the GS sheet.

Recommendationi. From the experimental investigation, it is observed that most of the columns failed in shear, this type of failure occurred due to presence of weak concrete at the failure zone for further research the columns should be casted carefully so that each and every portion of the column may have uniform density of concrete.

ii. Major work is done on concrete filled steel tubular column is experimental. Still, there is a need for numerical study is needed to check the parameters which affect the ultimate strength.

iii. As the BNBC code has not thrown light, for calculating the strength of concrete filled steel tubular column, further research is needed.