Post on 29-Nov-2014
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Steel and composite bridges in Germany
State of the ArtUniv.-Prof. Dr.-Ing. G. Hanswille
Institute for Steel and Composite StructuresUniversity of Wuppertal
Germany
Univ.-Prof. em. Dr.-Ing. Dr. h.c. G. Sedlacek
Institute for Steel and Lightweight StructuresRWTH Aachen
Germany
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Introduction
Typical composite road bridges with open sections and box girders
Composite box girders with wide cantilevering concrete decks
Composite bowstring arches
Composite trusses
Composite bridges for small and medium spans
Cable stayed bridges
Canal bridges
Contents
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Very slender and aesthetic bridges due to the optimal combination .of high tensile strength of structural steel and the high compressive strength of concrete High durability of normal reinforced concrete decks due to restrictive crack width limitation. In comparison with steel bridges composite bridges have a better behaviour with regard to freezing in winter.Because the low dead weight of the composite bridges deck is, composite bridges have advantages with regard to the foundation and settlements of supports.Due to innovative erection methods composite bridges are often used for bridges over passing existent railways or highways without any restrictions for the traffic. Where existing freeways with two lanes are widened the short erection time of composite bridges avoids longer restrictions for traffic.
Advantages of composite bridges
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Werra-Bridge Einhausen
Composite Bridges with open and closed cross-sections
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5
16,75m12,75m 2,002,00
2,5752,5755,80
4,30 4,308,15m
35 cm45 cm
2,5%
6,80m
55cm 40 cm
25cm
25cm
3,007,15
1,80
45cm2,5%
2,5%
box girder
5,8035cm
1,803,00
25cm
cross-section with two separated box girders
airtight welded box girders
plate girder bridge with three rolled or welded main girders
Typical cross-sections for composite bridges
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view
5,00
11,00 11,003,25
25,25 m
2875 1300 5700 mm 1300 2475
cross-section at midspan
7000 mm
55 72,5 80,0 80,0 80,0 75,0 72,5 67,0 58,0 40,0680,0
290460
Bridge Schleusetal
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Bridge Schleusetal
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Bridge Schleusetal
transportation of steel girderson site
erection of steel girders bycranes
casting of the concrete deck bymoveable formwork
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Examples for formwork systems
retractable console
wedges
formwork tables
formwork tables on temporary consoles
scaffold beam
rollers
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Bridge across the river Ruhr near Hagen-Freeway A1
14,50 14,50 1,961,96 1,50 1,50
3,01 3,012,502,50 6,00 6,002,502,50 3,52 3,52
35,06m
73,48m 95,77m 71,83m
4,00m2,70 1,30
1,25
4,50 4,
76 3,20 3,46
3% 3%
view
cross-sectionat midspan
cross-sectionat supports
concrete end cross girder
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Bridge across the river Ruhr near Hagen-Freeway A1
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30.00
3.0011.50
2.00
6.23 4.36
6.92
2.00
4.01 6.99 4.00
3.75
concrete C 50/60
concrete C35/45
cross-section at midspan
cross-section at support
0 1 2 3 4 5
95.00 154.00
362.00
68.00 58.00470.00
3.30
7.00
3.30
7.00
3.30
3.30
3.30
HHW 366.00
3.7511.50
4.39
0,52 0,34
0,35
Bridge Neuötting -Double composite box girder
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Double composite bridge Neuötting
box girder with double composite action at internal supports
composite bottom flange
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Box girders with corrugated webs
Bridge Altwipfergrund
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15
30,5 40,0 42,0 42,0 42,0 42,0 42,0 36,0
316,5
view
cross-section
36,75
2,25 14,501,75 1,50
2,2514,50
7,75 7,75
6% 4%0,00 0,00 4%6%15%35404%
18,50 18,25
3,603,35 3,353,355,905,90 5,655,65
-2,95
1,60
Bridge Langerfeld – Freeway A1
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Langerfelder Bridge – Highway A1
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Langerfelder Bridge – Highway A1Detailing at internal supports
elastomerbearings wedge
shaped bearing plate
transverse stiffener for hydraulic press
support stiffener
plate for jacking supports by hydraulic press in case of exchanging bearings
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Bridge Albrechtsgraben
Composite box girders with wide cantilevering concrete decks
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Composite box girders with wide concrete decks
Bridge Reichenbachtal Bridge Elben
Bridge Schwarza Bridge Oehde
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Bridge Wilde Gera
3030 36 3642424242424242424242252m
Schweinfurt
DB
3,30
Wilde Gera14,50
1,80Erfurt
28,00m
10,0010,002,00 2,001,501,50
5,505,50
3,155,001,203,803,805,003,15 1,203535
longitudinal beamstransverse tension member
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Bridge Wilde Gera
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Bridge Wilde Gera – Highway A71
transverse framestransverse steel tension members
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Bridge Wilde Gera – Highway A71
cantilever erection of the arch
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Bridge girder during launching
Bridge Wilde Gera – Highway A71
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25
Bridge Albrechtsgraben - Highway A71
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140 130 120 110 100 90 80 70 60 50 40 30 20 10
55 60 70 70 70 45 40 40 45 70 60 50 45
770
150
29,0025,00
2,002,00
6,001,504,156,00 1,50 4,15
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Bridge Albrechtsgraben - Highway A71
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Different detailing of transverse tension members
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Joints between the longitudinal girders/box girders and the transverse tension members
Bridge SchwarzaBridge Albrechtsgraben
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pulling down joint horizontal loops
tension member
vertical stirrupps
Zs
Zs
Za
Dc
Zs,q
A A
section A-A
Detailing of the transverse tension members
outside longitudinal girder
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Acessment of different solutions for transverse tension members
complicate connection caused by the eccentricity between the tension member and the top flanges of the box girder
no significant stresses in the steel tension member due to local loads
slabs with constant depth and haunches in longitudinal direction are possible, uni-axial load transfer in transverse direction
higher stresses due to local loads. Resistance of the tension member to normal forces, bending moments and vertical shear should be considered
haunched concrete slab, expensive formwork, bi-axial load transfer in transverse and longitudinal direction
economical simple connections with the top flanges of the box girder and the secondary longitudinal girders
high stresses due to local concentrated wheel loads (Fatigue resistance)
a constant depth of the slab over the total width of the bridge deck is required, uni-axial load transfer in transverse direction
connectionsinternal forces in the tension member
geometry of the concrete slab
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Sequense of casting of concrete
Method I : continuous in one direction
Method II: continuous in one direction but regions at internal supports are casted in a second step after the concrete in mid-span regions is effective
Method III: span-wise in reverse direction
Method I
Method II
Method III
10 20 30 40 50 60 70 80 90 100 110 120
1 ‰
45 55 70 70 70 70 70 70 70 55 45690
cross-section28,50
3,80
70,0
17,53 x 15,0 3 x 15,0 3 x 15,017,5 7,57,57,5
70,0
121110987654321
111091276583214
910111256781234
7,5
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Method I
Method II
Method III
My= -105,3My= -103,2 My= -107,5
My= -31,9 My= -31,9My= -45,4My= -43,7
My= 27,2 My= 28,1My= 25,6
My= -32,5 My= -33,5
My= 27,3 My= 25,4My= 26,5[My in MNm]
++
+
+ + +
-
-
-
--
- -
bending moments acting on the composite sectiondue to dead weight of concrete
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formwork carriage for cantilevers
Formwork carriage running on the top of the deck
formwork tables on temporary consoles
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Bridge Wilde Gera
Formwork carriage running on the top of the deck
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formwork carriage for outer cantilevers
Formwork underneath the concrete deck
Bridge Albrechtsgraben
formwork tables on temporary consoles
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Bridge Schwarza
Formwork underneath the concrete deck (system Kirchner)
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Exchange of concrete decks
Normally it is a general requirement in Germany to have separate bridges for each traffic direction in order to be able to divert the full traffic on the remaining bridge in case of major maintenance work on the other. The concrete deck is the most vulnerable part of a bridge section. With regard to the expected intensive increase of road traffic and local wheel loads in future, the concrete deck must be regarded as a wearing part in contrast to the steel structure with implication of different lifetimes of the concrete deck and the steel structure.
In case of one main composite box girder for both traffic directions the flow of traffic has to be maintained in both directions just on one half of the bridge during a future replacement of the bridge deck. For this procedure the bridge deck will be partially cut out with high-pressure water method and will be replaced by a new bridge deck. During this procedure significant additional stresses result in the superstructure, which have to be considered during design and construction.
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Different possibilities for the exchange of the concrete slab
exchange over a quarter of the bridge in two steps
exchange of one half of the deck with additional horizontal bracing
A
Horizontal bracing
B
C
B1
B2
exchange of one half of the deck The width of the span is the most important factor for choosing the different methods. Method A can only be used for spans up to 50 m. Methods B or C are possible for the exchange of the concrete deck of bridges with larger spans of up to 100 m.
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418,30 m
44,70 44,7056,056,0 72,80 64,072,80
00 10 20 30 40 50 60 703,8%
5600 23103800
38005600
2,5%
3800
38002310
3785
Bridge Oehde – Freeway A1
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Bridge Oehde – Freeway A1
transverse tensionmember
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Bridge Oehde – Freeway A1
P1 P3 P2 P6 P4 P5 P9 P7 P8 P11 P10 P13 P12 P15 P14
concrete deck withpartially prefabricated
concrete elements
launching of the bridge withpartially prefabricated concrete
elements
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Composite bowstring arches
Saalebridge Besedau
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Composite bow string arches
Composite bow string arches with concrete decks are an often used system where the construction depth is limited e.g. for bridges over canals and rivers.The reinforced concrete deck is connected with the steel structure by horizontal bracings at the end of the bridge and is acting as a tension member in the main system.
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Normal forces in the concrete tension member
N= Ns+Na
Ns,cr Ns,crn
Ns,2
Na,2
Ns
Na
ΔNt,s
εs,2 εs,m
Ns= Ns,2 + ΔNt,s
Na= Na,2-ΔNts
N
The concrete member acts as a tension member in the main system.
For the normal forces in the concrete member the effects of tension stiffening of concrete between cracks should be considered.
Na= Na,2-ΔNts
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Bridge Ladbergen near Ladbergen– Highway A1
cross-section1500 1500
10100 9750 9750 101002000
800
1538
924
00
800
1538
924
00
view
plan
1500
104270
1985
019
850
2000
3958
end-bracing
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Detailing of composite bowstring arches
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Composite trusses
Bridge St. Kilian
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Composite truss bridge with double composite action – Bridge Nantenbach across the river Main
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view
C
C
B
B
C
C A
A
8 9 10
12,5 ‰
83,20m 208,00m 83,20m
25
49
6,80
1,20
3,953,958080
R=2650,00m
14,30
1,00
20 20
501,4
0
R=2650,00m
14,3020 20
501,4
0
15,26
2,00
1,20
2,60 2,602,60
80801,60 1,60
14,3020 20
R=2650,00m
6,80
1,10-
1,80
501,4
0
8080
1,00
1,00
Composite truss bridge with double composite action – Bridge Nantenbach across the river Main
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Composite truss bridge Kragenhofer
view
249,6058,40 73,60 58,4059,20
cross-section
143004700 2200 260022002600
5600 43504350
1552,35R=
400
70028
0
9000
26
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Bridge St. Kilian
28,5 m
5,0 m
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Bridge St. Kilian
steel trusses with hollowsections and cast iron nodes
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Composite bridges for small and medium spans
Bridge Oberhartmannsreuth
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Composite bridges with rolled sections for small an medium spans
Advantagesshort construction timesimple erection method because of no steelwork on site. steelwork only in the shopsmall total depth of the composite sectionconcrete slab without any pre-stressing
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Longitudinal reinforcement at internal supports
bottom layer of reinforcementAs,min = ∅16 a=10 cm
bQRT L+lb
The longitudinal reinforcement at internal supports should be placed over a length not smaller than L= 0,15 LSt where LSt is larger span length adjacent to the support considered.
at the end of the steel girder the number of shear connectors should be increased due to local introduction of the tensile force in the reinforcement in the composite section.
In case of sagging bending moments at internal supports due to temperature effects, traffic loads and settlements of supports for the tensile forces in the bottom flange a connection by steel plates or studs in combination with loops is required.
L+lb concentrated shear connectors at the end of the girder
lb-anchorage length of the reinforcement
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Detailing of transverse supporting beams in concrete
b>bmin b>90 cmbmin = 80cm (indirect support )
bmin= 60 cm (direct support)
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Detailing of partially prefabricated concrete elements
4,02,5
1,021
≥Cnom= 4,5cm
seal
hc
the depth of the concrete above the prefabricated elements hc should be not less than 20 cm within the traffic lanes. in other regions hc should not be less than 15 cm.
≥3cm
≥2,5 cm
Elastomeric support strips with a thickness of 2 cm and a width of 3 cm. The minimum value of pressing should be 3-5 mm and the maximum value should not exceed 10 mm.
mortar
shear reinforcement
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Casting of concrete
in case of smaller span length the transverse supporting beams and the concrete slab should be casted in one operation.
in case of larger span length or for bridges with a big total length at first the midspan regions and subsequently the internal supports and the transverse supporting beams should be casted.
L
0,15 L
casting of mid-span regions
casting of supporting beams and the slab at internal support
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VFT-Bridges with welded or rolled I-sections
steel girder in the shop
transport on site
installation by crane
steel girderprecastedconcrete flange
in situ concrete slab
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VFT-Filler beams
shear connection
3200
640
rolled section
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VFT-Filler beams
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Preflex - Beams
steel girder
prestressedcomposite bottom flange
The Preflex-Beam is a girder with a pre-stressed composite bottom flange where the pre-stressing is applied by elastic bending of the steel girder.
The pre-stress causes a higher bending resistance and a high flexural stiffness. Therefore the deflections under serviceability conditions very small. This type of beam is often used for railway and road bridges where the available construction depth is highly restricted. Ratios of span to structural depth up to 45 are possible for road bridges.
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Preflex Girders – pre-stressing of the concretebottom flange
campered steel girder
pre-stressing forces Fvapplied to the steelgirder (elastic bending)
casting of the concretebottom flange
removing of theprestressing force Fvafter hardening of concrete causescompressive stressesin the concrete bottomflange
casting of the concretetop flange on site
δFv Fv
Fv Fv
Fv Fv
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Composite bridge with Preflex-Girders
Hermann-Lieberum Bridge in Leipzig
continuous beam, span 33 m and construction depth 130 cm
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Cable stayed bridges
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53,24 64,554 64,554 64,554 64,554 64,554 334,82 61,76
396,132 376,412
D C
10 20 30 40 50 60 70 80 90
cable stayed bridge Wesel across the river Rhein
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Cable stayed bridge Wesel across the river Rhein
cross-section axes 10 - 70
550 4250700
2800 4250700 550
550 400 5506150 6150
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Cable stayed bridge Wesel across the river Rhein
cross-section axes 70 - 90
35008750300087503500
5900 59002000
13800
2,5% 2,5%
77107710
27500 mm
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Joint between the steel and the concrete section – concreteend cross girder
concrete end cross girder
joint with overlapping steelplates and headed studs
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concrete end cross girder
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71
4000
3295-3971
400
500
3000 30002000
4000
1000
1000
+145,30m
.+15,90
Pylon in high strength concrete
concrete section
composite section
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cables
Use of parallel strand cables of galvanizedwaxed and PE-coatedstrands instead of traditionally used fullylocked coil ropes.
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1070
80 90
stages I and II
stage III
stages III to VIII
stage IX
erection stages
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Canal bridges
canal bridge Lippe
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75
57,10106,20m57,10 6,30
10x5,7110x5,3110x5,3110x5,71
7,81
3,98 3,9834,04
cross-section
view
42,00 m
10 20 30 40
Canal bridge Magdeburg
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Canal bridge Magdeburg
total length 228 mspan length 57,1 m – 106,2 m – 57,1 mStructural steel 9.500 t
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77
1900
740
4819
2440
Canal bridge Magdeburg
1087
.5
740
transverse frame
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Launching of the bridge
stage 2
stage 11
stage 17
stage 22
40
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Canal-bridge Lippe
A B C D
24,00m 24,80m 24,00m
4,75 28,00m 3,00
+56,50 NW
2,21 2,16 10,82 10,82 2,16 2,21
7,84
LT7 LT6 LT5 LT4 LT3 LT2 LT1
LT7 LT6 LT5 LT4 LT3 LT2 LT1
+56,50 NW
3,0028,00m4,75
30,40m2,21 4,33 4,33 4,33 4,33 4,33 4,33 2,21
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Canal-bridge Lippe
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7th Japanese – German Bridge Colloquium Osaka 2007
Thank you very much for your attention