4. Construction methods (the way the concrete deck is...

4. Construction methods

(the way the concrete deck is applied)

• weather dependence • investment cost and labour intensity of usage of formwork• construction speed• requirements regarding durability• connection steel supporting structure and concrete deck • temporary support provisions• extra reinforcement for connecting prefab - in situ parts

• in situ casted• use of prefab deck elements (full or half depth precast)


In-situ casted

advantages:- simple transport- simple adaptation of cross section- variances in sequence steel-concrete- uniform shear connection over the length- durable connection between steel – concrete- no extra reinforcement required

disadvantages:- no conditonal hardening- required formwork construction- long construction time (scaffolding,

reinformcement, casting, etc.)


In-situ casted

temporary scaffolding: conventional construction, supported by the upper flange


In-situ casted

temporary scaffolding: conventional system, supported by the lower flange


In-situ casted

temporary scaffolding: movable system supported by the upper flange


In-situ casted

scaffolding used only once


Use of prefab deck elements

hoisting of prefab deck panels

half depth

full depth

Large span length and therefore the use of timber girders as scaffolding is difficult.



advantages:- short construction time- manufacturing in shop- sequence of connecting steel - concrete

disadvantages:- concentration location of shear connection- extra reinforcement- dimension tolerances- splice between steel and concrete



sliding of concrete deck

studs connected afterwards

Cross-section at spacingCross-section between spacings



sliding of concrete deck

studs connected already

Cross-section between spacings Cross-section at spacing

studs

5. Erection methods

In contrast with concrete bridges and steel bridges, steel-concrete bridges, specifically the roadway, can be erected in a great variety of ways. The basis of the various erection methods is the fact that a certain level of tensile stresses in the concrete roadway is undesirable and the stress distribution caused by tension in completed condition of the bridge can be strongly controlled by the way of erection of the roadway. Tensile stresses in the concrete causes:

• forming of crack, reducing the durability of the roadway and the underlying structure

• reduction of the axial and bending stiffness of the composite steel-concrete cross section

• Increase of steel stresses

The most common solution of this problem is allowing but limiting of the width of the crack by means of reinforcement and the somewhat prestressing of the roadway,

5. Erection methods

a. certain casting sequenceb. application of temporary supportsc. support displacementsd. certain time of dowel activatione. prestressing in longitudinal directionf. combination of items a through e.

5. Erection methods

Certain concrete casting sequence

a1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

1

fase 0 LC 1

fase 1

fase 2

fase 3

fase 4

fase 5

fase 6

LC 5

LC 2

LC 2

LC 5LC 4

LC 4

LC 4LC 3LC 2

LC 4LC 3 LC 4LC 2 LC 2

LC 5

LC 2LC 3LC 4 LC 5

LC 2LC 4

LC 2

LC 4LC 3 LC 2

LC 4LC 5

LC 4LC 3LC 2

LC1Self-weight steel structureLC2Self-weight concrete (before hardening)LC3Self-weight concrete (after hardening)LC4Self-weight scaffoldingLC5Other non-permanent loadings caused by personel, material, equipment, etc.)

5. Erection methods

Certain concrete casting sequence

b1 2 3 8 9 7 6 5 4 14 15 13 12 11 10 19 20 18 17 16

1 23 5 4 7 6

fase 0 LC 1

fase 1 LC 2LC 4LC 5

LC 5LC 4LC 2LC 2

LC 4LC 3

fase 2

LC 4LC 3LC 2fase 3 LC 2

LC 5LC 4


LC 5LC 4


LC 5LC 4

LC 4LC 3LC 2fase 6

5. Erection methods

Application of temporary supports

staal-beton brug

vijzelvulling 150 mm hardhoutonderstopping hardhout/staalplatenstalen HEB ligger

Trestle element H=1000

Trestle element H=1600

2x onderslag min. HE 300Bverstijvingsschotjes t.p.v. Trestle poten

puinverharding op zandpakket

5 dragline schotten 4000x1000x100

staalplaat 1500x1500x75

•supported with initial positive displacement (by external loading) of the steel structure•supported but without external loading to the steel structure.

5. Erection methods

Application of temporary supports

Without temporary supports

Temporary supports without prestressing the girder

Temporary supports and prestressing the girder

5. Erection methods

Support displacements

fase 0 LC 1

fase 1

fase 3

fase 2 LC 3LC 5

•upwards displacement of all intermediate supports at the same time and, after connecting the concrete deck to the steelstructure, lowering the supports•the in turn vertical displacement of the intermediate supports•downwards displacement of end supports

Fase 0

Fase 1

Fase 2

Fase 3

5. Erection methods

Prestressing

5. Erection methods

Design example

Betonnen rijvloer

Stalen plaatligger

Concrete deck

Main steel girder

5. Erection methods

Design example

Adapted erection methodsVariant 1.1: pouring of sequential parts Variant 1.2: first pouring the fields and after that above the in-between supportVariant 1.3: first pouring above the in-between support and then at the fields

fase 0 LC 1

fase 1 LC 2LC 4LC 5

LC 5LC 4LC 2LC 2

LC 4LC 3

fase 2


LC 5LC 4


LC 5LC 4


LC 5LC 4

LC 4LC 3LC 2fase 6

fase 0 LC 1

fase 1 LC 2LC 4LC 5

fase 2LC 4LC 3LC 2

LC 5LC 4LC 2

fase 3 LC 2

LC 4LC 3

fase 4 LC 2

LC 4LC 3

fase 5 LC 2

LC 4LC 3

fase 6 LC 2

LC 4LC 3

LC 5LC 4LC 2

LC 2LC 4LC 5

LC 4LC 2

LC 5

5. Erection methods

Design example

Adapted erection methodsVariant 1.1: pouring of sequential parts Variant 1.2: first pouring the fields and after that above the in-between supportVariant 1.3: first pouring above the in-between support and then at the fields

Topside steel girder inbetween support

5. Erection methods

Design example

Application of temporary supportsVariant 2.1: ten temporary supports per spanVariant 2.2: one temporary support per span

fase 0 LC 1

fase 1 LC 3LC 5

fase 2

fase 0 LC 1

fase 1 LC 3LC 5

fase 2

5. Erection methods

Design example

Application of temporary supportsVariant 2.1: ten temporary supports per spanVariant 2.2: one temporary support per span

Differences using 1 or many temporary supports on size of stresses is small

5. Erection methods

Design exampleApplication of upwards displacement of the in-between supportVariant 3.1: lifting the support by 0.1 m Variant 3.2: lifting the support by 0.5 mVariant 3.3: lifting the support by 1.0 mVariant 3.4: Lowering the end supports by 0.1 m

fase 0 LC 1

fase 1

fase 3

fase 2 LC 3LC 5

fase 0 LC 1

fase 1

fase 3

fase 2 LC 3LC 5

5. Erection methods

Design exampleApplication of upwards displacement of the in-between supportVariant 3.1: lifting the support by 0.1 m Variant 3.2: lifting the support by 0.5 mVariant 3.3: lifting the support by 1.0 mVariant 3.4: Lowering the end supports by 0.1 m

5. Erection methods

Design example

Time of dowel activation:4.1 activating dowels after the concrete has hardened4.2 activating dowels at the time of hardening process

Combination of construction methods:5.1 pouring fields first, after that at the supports and application of an intermediate support at the span centres5.2 temporary supports in span centres and lifting of the intermediate support by 0.5m (apply temporary supports after theintermediate support has been lifted)

5. Erection methods

Design example

Combination of construction methods:

5.3 lifting of the intermediate support by 0.1 m and pouring fields first, after that above the supports

5.4 lifting the intermediate support by 0.5 m, pouring fields first above the intermediate support and apply a temporary support at the span centres

5. Erection methods

Design example

Combination of construction methods

5. Erection methods

Design example

Combination of construction methods

Building Size of stresses Construction speedness variant steel concrete pouring sequence temporary supports lifitng dowel activating variant 1.2 - - * variant 2.2 ++ -- * variant 3.2 -- ++ * variant 4.2 -- 0 * variant 5.1 + 0 * * variant 5.2 + + * * variant 5.3 - 0 * * variant 5.4 + + * * *

13km length high speed line

Above crossings: 56m span, total length 112m

others 32 m single span

65 dB(a) during daytime and 55 dB(A) during night

Extra construction height (prestressed concrete) at mid span

Reinforcement in transverse direction (incl. effect of derailment) en prestresses in longitudional direction

Fabrication of 2 sections / day

Decisive for design of load caused by launching

Integral bridge

Integral bridge

25 m 25 m30 m80 m

4,5 m

15,0 m

10,0 m2,5 m 2,5 m

0,25 m0,25 m0,22 m

0,72 m

15,0 m

10,0 m2,5 m 2,5 m

0,25 m0,25 m

0,47 m0,97 m

VELDDOORSNEDE

STEUNPUNTSDOORSNEDE

Integral bridge

Integral bridge

0,6 2,3 2,3 2,3 2,3 2,3 2,3 0,6

15,0

7 palen vierkant 450 mm

MEI

LM M

EI

LMT passief B passief= + = −

6 62 2

∆ ∆ en

Integral bridge

Integral bridgeTop warmer than bottom Bottom warmer than top Type of deck

∆TM,heat (° C) ∆TM,cool (° C) Type 1: Steel deck 18 13 Type 2: Composite deck 15 18 Type 3: Concrete deck - Concrete box girder - Concrete beam - Concrete slab

10 15 15

5 8 8

Integral bridge with various materials used

Monolitic concrete: 85 mm per abutment

ZIP-girders, prefab concrete deck: 44 mm per abutment

Steel girders with concrete deck (casted in situ): 31 mm per abutment

29%

15%13%8%

15%

20%c reeppres tressadiabatic s hrinkagehardening shrinkage(norm al) shrink agem inim um tem perature

0%0%0%0%

47%

53%

c reeppres tres sadiabatic s hrink agehardening s hrinkage(norm al) shrink agem inim um tem perature

0%0% 12%6%

6%

76%

c reeppres tres sadiabatic s hrinkagehardening s hrink age(norm al) s hrink agem inim um tem perature

-100.0

-80.0

-60.0

-40.0

-20.0

0.0

20.0

40.0

0.1 1 10 100

years

brid

ge e

nd d

ispl

acem

ent [

m

in situ C35/45: total maximum

in situ C35/45: total minimum



prefab C45/55: total maximum

prefab C45/55: total minimum



composite C35/45: totalmaximumcomposite C35/45: totalminimum

Time considered

Kind of deck End displacement

Bridge deck alternative

in situ concrete prefab concrete Composite bridge deck elongation and contraction [mm/m’] t = ± 60 days Elongation -0.70 0.40 0.40 Contraction -1.50 -0.40 -0.70 t = 75 years Elongation -1.20 -0.20 0.40 Contraction -1.90 -0.90 -0.70



-200,0

-180,0

-160,0

-140,0

-120,0

-100,0

-80,0

-60,0

-40,0

-20,0

0,0

20,0

40,0

20,0 40,0 60,0 80,0 100,0 120,0 140,0 160,0 180,0

bridge length [m]

brid

ge e

nd d

ispl

acem

ent [

mm

]

. in situ C35/45: total maximum








composite C35/45: total maximum

composite C35/45: total minimum

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