EC bridge actions
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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
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
2 Action on bridges
- BS EN 1990, Annex A2, Table A2.1: y -factors for road bridges
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
3 Action on bridges
- BS EN 1990, Table A2.4(A): partial factors (EQU)
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
4 Action on bridges
- BS EN 1990, Table A2.4(B): partial factors (STR/GEO)
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
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
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
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)
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
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
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
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
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
9 Divisions of the carriageway into notional lanes
- Number and width of notional lanes (Tab. 4.1)
example: w = 11 m
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
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)
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
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
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
12 Load model 1 (EN 1991-2, 4.3.2)
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
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
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
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
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
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
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
16 Groups of traffic loads
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
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
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
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
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
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
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
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:
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
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
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
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
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
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
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
24 Wind actions (EN 1991-1-4, section 8)
- the wind distribution depends on the height of bridge and height over ground
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