EC bridge actions

B a u h a u s - U n i v e r s i t t W e i m a r

Chair of Modelling and Simulation of Structures Actions on bridges

1 Action on bridges

Content:

1 permanent actions 2 traffic loads 3 temperature actions variable actions 4 wind actions

Standard basis:

- Eurocode: BS EN 1990: Basis of structural design (EC 0)

BS EN 1991-1: Actions on structures (EC 1, part 1)

BS EN 1991-1-4: Wind actions

BS EN 1991-1-5: Thermal actions

BS EN 1991-1-7: Accidental actions

BS EN 1991-2: Traffic loads on bridges (EC 1, part 2)

BS EN 1992-1: Actions on structures (EC 2)

+ BS EN 199x/NA National Annexes



2 Action on bridges

- BS EN 1990, Annex A2, Table A2.1: y -factors for road bridges



3 Action on bridges

- BS EN 1990, Table A2.4(A): partial factors (EQU)



4 Action on bridges

- BS EN 1990, Table A2.4(B): partial factors (STR/GEO)



5 Types of actions (EN 1990:2002, 4.1.1)

- permanent actions (G): self-weight of structures (g)

fixed equipment and road surfacing (Dg)

settlement (Ds)

- variable actions (Q): imposed loads (q)

temperature (DT)

wind loads

- post tensioning: with and without bond

- accidental actions (A): impact from vehicles on bridge superstructure or piers

heavy wheel loads on pavements

impact on caps and safety barriers

- seismic actions



6 1 permanent actions (G)

- permanent loads from self weight of the components and building materials are to be taken

from EN 1991-1

settlement (Ds)

- they basically belong to the permanent actions, but must be arranged unfavourably

as variable action

- probably settlement: Dsm = 1 cm (SLS)

- possible settlement: Dsk = 1 cm (ULS)



7 2 Traffic Loads on bridges (EN 1991-2)

General

- Field of application: loaded lengths less than 200 m (For very long loaded lengths, see

National Annex)

- 3 steps of load assumptions:

I Traffic load models

Vertical forces: LM1, LM2, LM3, LM4

Horizontal forces: braking and acceleration, centrifugal, transverse

II Groups of loads

gr1a, gr1b, gr2, gr3, gr4, gr5

characteristic, frequent and quasi-permanent values

III Combination with actions other than traffic actions



8 Divisions of the carriageway into notional lanes

- Carriageway width w

width measured between kerbs (height more than 100 mm recommended value)

or between the inner limits of vehicle restraint systems



9 Divisions of the carriageway into notional lanes

- Number and width of notional lanes (Tab. 4.1)

example: w = 11 m



10 Load models (vertical loads)

The specified load models do not describe actual loads.

The recommended values of the load models in EN 1991-2 are chosen and adapted to

correspond with the actions of traffic in the year 2000.

- Load model 1

Concentrated and distributed loads (main model general and local verifications)

- Load model 2

single axle load (semi-local and local verifications)

- Load model 3

Set of special vehicles (general and local verifications)

- Load model 4

Crowd loading (general verifications)



11 Load model 1 (EN 1991-2, 4.3.2)

- For the determination of general effects, the tandems travel centrally along the axes of

notional lanes

- For local verifications, a tandem system should be applied at the most unfavourable location

DIN EN 1991-2

/NA

Qik [kN]

qik [kN/m]

Qi Qik [kN]

qi qik [kN/m]

Lane 1 300 9,0 300 12,0

Lane 2 200 2,5 200 6,0

Lane 3 100 2,5 100 3,0

More Lanes 0 2,5 - 3,0

remaining

area

0 2,5 - 3,0



12 Load model 1 (EN 1991-2, 4.3.2)



13 Load model 2

- single axle load Qak with Qak equal to 400 kN

Recommended value: Q = Q1

(see National Annex)

Load model 3

- Where relevant, models of special vehicles should be defined

Load model 4

- Crowd loading, if relevant, uniformly distributed load (which includes dynamic amplification)

equal to 5 kN/m



14 Dispersal of concentrated loads (EN 1991-2, 4.3.6)

a) Pavement and concrete slab

1 Wheel contact pressure

2 Pavement

3 Concrete slab

4 Middle surface of concrete slab

b) Pavement and orthotropic deck

1 Wheel contact pressure

2 Pavement

3 Bridge floor

4 Middle surface of the bridge floor

5 Transverse member



15 HORIZONTAL FORCES : Braking and acceleration (EN 1991-2, 4.4.1)

- should be calculated as a fraction of the total maximum vertical loads

corresponding to the Load Model 1 likely to be applied on Lane Number 1

- For Lane 1: Qlk= 360 + 2.7 L L length of the deck

Centrifugal forces (4.4.2)

- r horizontal radius of curvature of the carriageway centreline [m]

- Qv total maximum weight of vertical concentrated loads of the tandem systems of LM1



16 Groups of traffic loads



17 Fatigue load models (EN 1991-2, 4.6)

- Fatigue Load Model 3 (single vehicle model)

- Highway bridge with two lanes in each direction and a high proportion of truck

- model consists of four axles

- weight of each axle is equal to 120 kN



18 Collision forces on piers / supporting members (EN 1991-2, 4.7.2)

- Forces due to the collision of abnormal height or aberrant road vehicles with piers or

with the supporting members of a bridge should be taken into account.

- The regulations of EN 1991-1-7

Collision forces on decks

- Impact loads from road under bridges according to DIN EN 1991-1-7:2010-12, 4.3.2 are to

consider only the check of position stability of the superstructure



19 Actions from vehicles on the bridge (EN 1991-2, 4.7.3)

- Vehicle on footways and cycle tracks

- Impact forces on kerbs

- Impact forces on safety barriers



20 Thermal actions (EN 1991-1-5)

- Daily and seasonal changes will result in variations of the temperature distribution within

individual elements of a structure

- The temperature distribution may be split into the following four essential constituent

components:



21 Thermal actions

- For bridges, constant and linear temperature component is to consider only

- Outside air temperature between Tmax = +37C and Tmin = -24C

- Setup temperature T0 usually average value with T0 = +10C

- max. Variations in the pos. / neg. temperature component

DTN,pos = Te,max T0 DTN,neg = T0 Te,min

- Total variation in the temperature constant proportion

DTN = Te,max Te,min = DTN,pos DTN,neg



22 Thermal actions

- bridge decks are grouped in 3 types

- For bridge generally: the constant and linear temperature components is considered only

- Table 6.1: Recommended values of linear temperature difference component



23 Thermal actions

- Example: Top warmer: 8 cm pavement ksur = 0,82 DTM,heat = 15 C 0,82 = 12,3 C

Bottom warmer: independent of pavement ksur = 1,0 DTM,cool = -8 C 1,0 = -8 C



24 Wind actions (EN 1991-1-4, section 8)

- the wind distribution depends on the height of bridge and height over ground

EC bridge actions

Documents

u s u n

e r s i t t w e i

bridges en

traffic actions b

types of actions en

wind actions bs en

bridges bs en

accidental actions bs