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Bridge Design K7005B

Loads according to Eurocode

2014-09-05Jörgen Andersson

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Bro 2004 (the old swedish code)

• The Swedish General Code for the design and improvement of bridges.

• From 2009-06-01, Bro 2004 may not be used in calculations of new bridges.

• A new Code ”TRVK Bro” is used to guide the designers in the use of the Eurocodes.

• Nevertheless, the basic structures are similar, and the Code will also be in use for several years to come, at least for older bridges.

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Eurocodes

• The work to create a European code began in 1975.• Sweden joined in 1989, when the work was transferred to CEN.• Pre-standards (ENV) were published between 1990-2000.

– Voluntary to use.– Early example: Öresund bridge.

• Definite standards (EN)– All parts are now finalized.– Mandatory according to certain rules for the transition period.– National codes could be used until the end of 2010.

• SS-EN (Swedish version, generally translated).• NA (National Annex, some adjustable parameters for each country).

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Eurocodes, overview

EN 1990 Eurocode 0: Basis of Structural DesignEN 1991 Eurocode 1: Actions on structuresEN 1992 Eurocode 2: Design of concrete structuresEN 1993 Eurocode 3: Design of steel structuresEN 1994 Eurocode 4: Design of composite steel and concrete structuresEN 1995 Eurocode 5: Design of timber structuresEN 1996 Eurocode 6: Design of masonry structuresEN 1997 Eurocode 7: Geotechnical designEN 1998 Eurocode 8: Design of structures for earthquake resistanceEN 1999 Eurocode 9: Design of aluminium structuresIn total: 59 separate standards, approx. 7000 pages.

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Loads acting on a bridge

Overburden (Överlast)

Earth pressure

Wind

Foundation movements

Self weight

Temperature loads

Traffic

Breaking forces

Shrinkage Pavement Shrinkage

Traffic

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Action classifications• Variation in time:

– Permanent actions: Dead weight, pavement, shrinkage etc.– Variable actions: Traffic, wind etc.– Accidental actions: Explosion, impact etc.

• Variation by origin:– Direct– Indirect (shrinkage etc.)

• Variation by spatial variation (in space):– Fixed– Free

• Variation by nature and/or structural response:– Static– Dynamic

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Permanent loads• Self-weight

– Unhardened concrete: 26 kN/m3

– Reinforced concrete: 25 kN/m3

– Concrete without reinforcement: 24 kN/m3

– Steel: 77 kN/m3

• Surfacing• Earth Pressure• Water Pressure• Settlements of the supports

– Vertical and horizontal• Shrinkage• Prestressing forces

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Variable loads• Traffic loads• Fatigue loads• Surface loads• Braking load• Braking sideways• Overburden• Temperature loads• Wind loads

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Self-weight• Steel

77 - 78.5 kN/m3

• ConcreteReinforced: 25 kN/m3

No reinf.: 24 kN/m3

Wet: 26 kN/m3

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Self-weight• Non-structural equipment

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Shrinkage• Three kinds of shrinkage according to EN 1992-1-1:

– Thermal shrinkage at early age.– Autogenous shrinkage (självkrympning).– Drying shrinkage.

• Shrinkage should be calculated for:– Persistent design situation at traffic opening.– Persistent design situation at infinite time.

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Creep• Modular ratio for short-term loading:

• Modular ratio for long-term loading:

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Traffic loads• The number of notional lanes are depending on the carriageway

width:

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Traffic loads

Tandem System (TS)Lane 1: αQ = 0.9Lane 2: αQ = 0.9Others: αQ = 0

Uniformally distributed loads (UDL):Lane 1: αq = 0.7Lane 2: αq = 1.0Others: αq = 1.0

• Load Model 1 (LM1) According to EN 1991-2, 4.3.2(1) (a)• Consists of two partial systems:

– Double-axle concentrated loads (Tandem System, TS).– Uniformly distributed loads (UDL system).

• Adjustment coefficients are given in the National Annex:

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Load Model 1 (LM1)

Tandem System (TS)Lane 1, 2: αQ = 0.9 Others: αQ = 0

UDLLane 1: αq = 0.7 Others: αq =1. 0

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Torque• Box-girder bridges are subjected to torque moments due to eccentric

loading of LM1.• The St Venant torsional stiffness of a box section:

– Where Ω represents the area bordered by the midplanes of the internal elements.

• If the section is located in a cracked zone, the slab thickness is reduced to one half, an example:

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Traffic Load Groups

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Loads acting on a bridge:

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Combinations of actionsDesign situations:• Transient design situations:

– For the structural steel alone under its self-weight (launching etc).– During and after concreting of each slab segment.

• Persistent design situations:– At traffic opening.– At infinite time.

• ULS: Ultimate Limit State (other than fatigue).

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Combination of actions

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Combinations of actions - ULS• ULS (EQU) – (Set A): Static equilibrium• ULS (STR/GEO) – (Set B) or (Set C): Design of structural

members, involving geotechnical actions.

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Combinations of actions - ULS

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Combinations of actionsULS (EQU) (Set A)

SKNr Permanenta laster d sup inf Gj,sup Gj,inf fmax fmin

1 Egentyngd 1.00 1.00 1.00 1.10 0.90 1.100 0.9002 Beläggning 1.00 1.10 0.90 1.10 0.90 1.210 0.8103 Jordtryck 1.00 1.10 0.90 1.10 0.90 1.210 0.8104 Stödförskjutning 1.00 1.10 0.00 1.10 0.90 1.210 0.0005 Krympning 1.00 1.10 0.00 1.10 0.90 1.210 0.000Nr GruppVariabla laster d Q1 0 1 2 (kar. fmax,h fkomb

Grupper av trafiklaster komb. frekv. kv.per. multi) huvudlast

6 LM1 TS 1.00 1.50 0.75 0.75 0.00 1.00 1.500 1.1257 LM1 UDL 1.00 1.50 0.40 0.40 0.00 1.00 1.500 0.6008 Broms-, acc. TS 1.00 1.50 0.75 0.75 0.00 0.60 0.900 0.6759 Broms-, acc. UDL 1.00 1.50 0.40 0.40 0.00 0.60 0.900 0.36010 Centrifugalkraft 1.00 1.50 0.75 0.75 0.00 0.60 0.900 0.67511 Sidokraft, TS 1.00 1.50 0.75 0.75 0.00 0.60 0.900 0.67512 Sidokraft, UDL 1.00 1.50 0.40 0.40 0.00 0.60 0.900 0.36013 1b LM2 1.00 1.50 0.00 0.75 0.00 1.00 1.500 0.00014 LM1 TS 1.00 1.50 0.75 0.75 0.00 0.75 1.125 0.84415 LM1 UDL 1.00 1.50 0.40 0.40 0.00 0.40 0.600 0.24016 Broms-, acceleration 1.00 1.50 0.00 0.00 0.00 1.00 1.500 0.00017 Centrifugalkraft 1.00 1.50 0.00 0.00 0.00 1.00 1.500 0.00018 Sidokraft 1.00 1.50 0.00 0.00 0.00 1.00 1.500 0.00027 Last på vägbank 1.00 1.50 0.75 0.75 0.00 1.500 1.12528 2) Vindlast 1.00 1.50 0.30 0.20 0.00 1.500 0.45029 3) Temperaturlast 1.00 1.50 0.60 0.60 0.50 1.500 0.900

6.10partialkoeff.

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Combinations of actionsULS (STR/GEO) (Set B)

SKNr Permanenta laster d sup inf Gj,sup Gj,inf fmax,a fmin fmax,b fmin

1 Egentyngd 1.00 1.00 1.00 1.35 1.00 0.89 1.350 1.000 1.202 1.0002 Beläggning 1.00 1.10 0.90 1.35 1.00 0.89 1.485 0.900 1.322 0.9003 Jordtryck 1.00 1.10 0.90 1.35 1.00 0.89 1.485 0.900 1.322 0.9004 Stödförskjutning 1.00 1.00 0.00 1.35 1.00 0.89 1.350 0.000 1.202 0.0005 Krympning 1.00 1.00 0.00 1.35 1.00 0.89 1.350 0.000 1.202 0.000Nr GruppVariabla laster d Q1 0 1 2 (kar. fmax,ha fkomb fmax,hb fkomb

Grupper av trafiklaster komb. frekv. kv.per. multi) huvudlast huvudlast

6 LM1 TS 1.00 1.50 0.75 0.75 0.00 1.00 1.125 1.125 1.500 1.1257 LM1 UDL 1.00 1.50 0.40 0.40 0.00 1.00 0.600 0.600 1.500 0.6008 Broms-, acc. TS 1.00 1.50 0.75 0.75 0.00 0.60 0.675 0.675 0.900 0.6759 Broms-, acc. UDL 1.00 1.50 0.40 0.40 0.00 0.60 0.360 0.360 0.900 0.36010 Centrifugalkraft 1.00 1.50 0.75 0.75 0.00 0.60 0.675 0.675 0.900 0.67511 Sidokraft, TS 1.00 1.50 0.75 0.75 0.00 0.60 0.675 0.675 0.900 0.67512 Sidokraft, UDL 1.00 1.50 0.40 0.40 0.00 0.60 0.360 0.360 0.900 0.36013 1b LM2 1.00 1.50 0.00 0.75 0.00 1.00 0.000 0.000 1.500 0.00014 LM1 TS 1.00 1.50 0.75 0.75 0.00 0.75 0.844 0.844 1.125 0.84415 LM1 UDL 1.00 1.50 0.40 0.40 0.00 0.40 0.240 0.240 0.600 0.24016 Broms-, acceleration 1.00 1.50 0.00 0.00 0.00 1.00 0.000 0.000 1.500 0.00017 Centrifugalkraft 1.00 1.50 0.00 0.00 0.00 1.00 0.000 0.000 1.500 0.00018 Sidokraft 1.00 1.50 0.00 0.00 0.00 1.00 0.000 0.000 1.500 0.00027 Last på vägbank 1.00 1.50 0.75 0.75 0.00 1.125 1.125 1.500 1.12528 2) Vindlast 1.00 1.50 0.30 0.20 0.00 0.450 0.450 1.500 0.45029 3) Temperaturlast 1.00 1.50 0.60 0.60 0.50 0.900 0.900 1.500 0.900

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6.10bpartialkoeff. 6.10a

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Combinations of actionsULS (STR/GEO) (Set C)

SKNr Permanenta laster d sup inf Gj,sup Gj,inf fmax fmin

1 Egentyngd 1.00 1.00 1.00 1.10 1.00 1.100 1.0002 Beläggning 1.00 1.10 0.90 1.10 1.00 1.210 0.9003 Jordtryck 1.00 1.10 0.90 1.10 1.00 1.210 0.9004 Stödförskjutning 1.00 1.00 0.00 1.10 1.00 1.100 0.0005 Krympning 1.00 1.00 0.00 1.10 1.00 1.100 0.000Nr GruppVariabla laster d Q1 0 1 2 (kar. fmax,h fkomb

Grupper av trafiklaster komb. frekv. kv.per. multi) huvudlast

6 LM1 TS 1.00 1.40 0.75 0.75 0.00 1.00 1.400 1.0507 LM1 UDL 1.00 1.40 0.40 0.40 0.00 1.00 1.400 0.5608 Broms-, acc. TS 1.00 1.40 0.75 0.75 0.00 0.60 0.840 0.6309 Broms-, acc. UDL 1.00 1.40 0.40 0.40 0.00 0.60 0.840 0.33610 Centrifugalkraft 1.00 1.40 0.75 0.75 0.00 0.60 0.840 0.63011 Sidokraft, TS 1.00 1.40 0.75 0.75 0.00 0.60 0.840 0.63012 Sidokraft, UDL 1.00 1.40 0.40 0.40 0.00 0.60 0.840 0.33613 1b LM2 1.00 1.40 0.00 0.75 0.00 1.00 1.400 0.00014 LM1 TS 1.00 1.40 0.75 0.75 0.00 0.75 1.050 0.78815 LM1 UDL 1.00 1.40 0.40 0.40 0.00 0.40 0.560 0.22416 Broms-, acceleration 1.00 1.40 0.00 0.00 0.00 1.00 1.400 0.00017 Centrifugalkraft 1.00 1.40 0.00 0.00 0.00 1.00 1.400 0.00018 Sidokraft 1.00 1.40 0.00 0.00 0.00 1.00 1.400 0.00027 Last på vägbank 1.00 1.40 0.75 0.75 0.00 1.400 1.05028 2) Vindlast 1.00 1.40 0.30 0.20 0.00 1.400 0.42029 3) Temperaturlast 1.00 1.40 0.60 0.60 0.50 1.400 0.840

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6.10partialkoeff.

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