Traffic Actions

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EN1991-2 – Railway traffic actions

and concrete bridge example

Mungo Stacy

Principal Engineer, Parsons Brinckerhoff

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Agenda

• EN1991-2 Railway traffic actions

• Example: combination of actions

• Example: concrete design for bending and shear

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Agenda

• EN1991-2: Railway traffic actions



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Rail traffic loads

• Normal traffic on mainline railways represented by 2 load models, based on UIC 776-1:

– LM 71: Simply supported

– LM SW/0: Continuous bridges

• These are static effects, need to be factored

• Formed into load groups, then combined with other actions

Date 26.02.10 7Design of bridges to EUROCODES

EN 1991-2: Load model 71

• LM 71 represents normal rail traffic


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EN 1991-2: Load model SW/0

• LM SW/0 used for continuous structures


EN 1991-2: Other load models

• Additional load models:

– LM SW/2: Heavy loads

– High speed load model (HSLM): Passenger trains > 200km/h

– Unloaded train: used in stability check

– ‘Real Trains’ defined in Annex D: used for fatigue


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EN 1991-2: Classification factor

• Static effects multiplied by classification factor

• This ‘classified vertical load’ allows for lines carrying lighter or heavier traffic

• Most secondary actions (e.g. nosing) also factored by


EN 1991-2: Dynamic effects

• Dynamic effects considered using quasi-static approach

• Multiply static effects by dynamic factor

• Depends on determinant length L


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EN 1991-2: Determinant length


EN 1991-2: Dynamic analysis

• Need to check if full dynamic analysis required

• Quasi-static methods (dynamic factor ) do not predict resonance effects from high speed trains

• Flowcharts provided in EN 1991-2, Figure 6.9

• Distinction between ‘simple’ and ‘complex’ structures (simple –represented by line beam)


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Dynamic analysis

• Flowcharts used to determine if dynamic analysis needed

• Extensive guidance provided on dynamic analysis

• Focus on high speed routes


Dynamic analysis

• Flowcharts used to determine if dynamic analysis needed

• Extensive guidance provided on dynamic analysis

• Focus on high speed routes


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EN1991-2: Load distribution

Rules given for distribution of vertical and horizontal loads:

• Eccentricity of vertical loads (6.3.5)

• Transverse distribution by sleepers and ballast (6.3.6.3)

• Longitudinal distribution of point load from rail to supports (6.3.6.1)

• Longitudinal distribution by sleepers and ballast (6.3.6.2)

• Equivalent vertical loading for earthworks (6.3.6.4)


EN1991-2: Secondary actions

• Secondary loads generally factored by but not by , combine with vertical loads:

– Centrifugal (6.5.1)

– Nosing force (6.5.2)

– Traction and braking (6.5.3)

• Track/structure interaction may need to be considered:


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EN1991-2: Aerodynamic effects

• Rules given for surfaces parallel to the track

– Vertical

– Horizontal

– Enclosures


EN1991-2: Derailment actions


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EN1991-2: Load combinations


Fatigue


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Fatigue load models –EN 1991-2 Annex D


Fatigue load models –EN 1991-2 Annex D


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Agenda




Note – UK partial factors used in example

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Actions on railway bridge

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EN1990: Combination of actions

21.07.2011 27Design of bridges to EUROCODES

EN1990: Combination of actions

Equation 6.10:

ULS verification (Persistent or transient design situations)


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Actions on bridge

Self Weights

Snow

Wind

Thermal

Execution

Accidental

Traffic

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Actions on bridge

Self Weights EN1991-1-1

Snow EN1991-1-3

Wind EN1991-1-4

Thermal EN1991-1-5

Execution EN1991-1-6

Accidental EN1991-1-7

Traffic EN1991-2

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Actions on bridge

Self Weights EN1991-1-1

Snow EN1991-1-3

Wind EN1991-1-4

Thermal EN1991-1-5

Execution EN1991-1-6

Accidental EN1991-1-7

Traffic EN1991-2

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Action

Dead load (concrete) Gk,DLconc

Superimposed dead Gk,SDL

Traffic LM71 Qk,LM71

Wind Qk,W

Thermal Qk,Th

Total

Combination of actions

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Action Char.(kNm)

ULS (kNm)

Dead load (concrete) Gk,DLconc

Superimposed dead Gk,SDL

Traffic LM71 Qk,LM71

Wind Qk,W

Thermal Qk,Th

Total

Combination of actions


Action Char.(kNm)

ULS (kNm)

Dead load (concrete) Gk,DLconc 198

Superimposed dead Gk,SDL 95

Traffic LM71 Qk,LM71 243

Wind Qk,W 25

Thermal Qk,Th 16

Total

Characteristic values

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Action Char.(kNm)

ULS (kNm)




Wind Qk,W 25

Thermal Qk,Th 16

Total

Characteristic values


Action Char.(kNm)

ULS (kNm)




Wind Qk,W 25

Thermal Qk,Th 16

Total

Partial factors

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Partial factors – UK values



Action Char.(kNm)

ULS (kNm)

Dead load (concrete) Gk,DLconc 198 1.35

Superimposed dead Gk,SDL 95 1.2

Traffic LM71 Qk,LM71 243 1.45

Wind Qk,W 25 1.7

Thermal Qk,Th 16 1.55

Total

Partial factors

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Action Char.(kNm)

ULS (kNm)

Dead load (concrete) Gk,DLconc 198 1.35

Superimposed dead Gk,SDL 95 1.2


Wind Qk,W 25 1.7


Total

factors


Action Char.(kNm)

ULS (kNm)

Dead load (concrete) Gk,DLconc 198 1.35 -

Superimposed dead Gk,SDL 95 1.2 -


Wind Qk,W 25 1.7


Total

factors

Permanentactions

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Action Char.(kNm)

ULS (kNm)




Wind Qk,W 25 1.7


Total

factors

Permanentactions

Variableactions


Action Char.(kNm)

ULS (kNm)




Wind Qk,W 25 1.7


Total

factors

Permanentactions

Leading

Accompanying

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factors

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Action Char.(kNm)

ULS (kNm)



Traffic LM71 Qk,LM71 243 1.45 1

Wind Qk,W 25 1.7 0.75

Thermal Qk,Th 16 1.55 0.6

Total

factors

Permanentactions

Leading

Accompanying

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Action Char.(kNm)

ULS (kNm)

Dead load (concrete) Gk,DLconc 198 1.35 - - 267

Superimposed dead Gk,SDL 95 1.2 - - 114

Traffic LM71 Qk,LM71 243 1.45 1 1.1 388

Wind Qk,W 25 1.7 0.75 - 32

Thermal Qk,Th 16 Not with wind -

Total 801

EN1990 A2.2 gives combination rules

Wind and thermal actions not considered simultaneously

Combination rules


Action Char.(kNm)

ULS (kNm)



Traffic LM71 Qk,LM71 243 1.45 1 1.1 388

Wind Qk,W 25 1.7 0.75 - 32


Total 801

Design effect

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EN19906.10


Action Char.(kNm)

ULS (kNm)



Traffic LM71 Qk,LM71 243 1.45 1 1.1 388

Wind Qk,W 25 1.7 0.75 - 32


Total 801

ULS Moment Combination(STR Persistent)

Actions on railway bridge - moment

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ULS

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Actions on railway bridge - shear

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ULS

EN19906.10


ULS Shear Combination(STR Persistent)

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EN19906.10


Action Char.(kNm)

ULS (kNm)

Dead load (concrete) Gk,DLconc 1.35 - -

Superimposed dead Gk,SDL 1.2 - -

Traffic LM71 Qk,LM71 1.45 1 1.1

Wind Qk,W 1.7 0.75 -

Thermal Qk,Th Not with wind

Total


EN19906.10


Action Char.(kN)

ULS (kN)

Dead load (concrete) Gk,DLconc 146 1.35 - -

Superimposed dead Gk,SDL 77 1.2 - -

Traffic LM71 Qk,LM71 189 1.45 1 1.1

Wind Qk,W 12 1.7 0.75 -

Thermal Qk,Th 6 Not with wind

Total


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EN19906.10


Action Char.(kN)

ULS (kN)



Traffic LM71 Qk,LM71 189 1.45 1 1.1 301

Wind Qk,W 12 1.7 0.75 - 15


Total 606


Actions on railway bridge - SLS

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SLS

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EN19906.14b


SLS Characteristic Combination


Action Char.(kNm)

SLS (kNm)




Wind Qk,W 25

Thermal Qk,Th 16

Total


EN19906.14b

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EN19906.14b

Action Char.(kNm)

SLS (kNm)

Dead load (concrete) Gk,DLconc 198 -

Superimposed dead Gk,SDL 95 -

Traffic LM71 Qk,LM71 243 -

Wind Qk,W 25 -

Thermal Qk,Th 16 -

Total



EN19906.14b

Action Char.(kNm)

SLS (kNm)

Dead load (concrete) Gk,DLconc 198 - -

Superimposed dead Gk,SDL 95 - -

Traffic LM71 Qk,LM71 243 - 1

Wind Qk,W 25 - 0.75

Thermal Qk,Th 16 - 0.6

Total

Permanentactions

Leading

Accompanying

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EN19906.14b

Action Char.(kNm)

SLS (kNm)

Dead load (concrete) Gk,DLconc 198 - - -

Superimposed dead Gk,SDL 95 - - -

Traffic LM71 Qk,LM71 243 - 1 1.1

Wind Qk,W 25 - 0.75 -

Thermal Qk,Th 16 Not with wind

Total



EN19906.14b

Action Char.(kNm)

SLS (kNm)

Dead load (concrete) Gk,DLconc 198 - - - 198

Superimposed dead Gk,SDL 95 - - - 95

Traffic LM71 Qk,LM71 243 - 1 1.1 267

Wind Qk,W 25 - 0.75 - 19


Total 579

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Note – Some UK National Annex values used in example

Agenda

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Concrete design to EN 1992-2 –ULS design example

ULS design example

Design load effects:

MEd = 801 kNm

VEd = 606 kN

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Section details

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Section details

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Material properties

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Material properties – design values

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Stress block

Section details

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Bending resistance

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Bending resistance

Reinforcement yield check

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Shear resistance – concrete only

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VEd = 606 kN

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VEd >VRd,cso shear reinforcement required VEd = 606 kN

Shear resistance – variable angle truss analogy

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Shear resistance – variable angle truss analogy

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Shear resistance – designed links

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VEd = 606 kN < OK


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Shear resistance – longitudinal steel

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Summary

• Railway traffic actions – EN1991-2

• Combination of actions – EN1990

• Concrete design example – EN1992-2

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Traffic Actions

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