1) y'i is a V-factor intended to define infrequent loads (see 2.2).

2) The boxed values of y* -j , vi » V2 ior 9r1 apply to routes with traffic corresponding to adjusting factors ocq; , otqj, Oqr and |3q equal to one. Those relating to UDL correspond to the most common traffic scenarios, in which an accumulation of lorries might occur, but not frequently. Other values of all Vi and vi factors, or of some of them, may be specified for other classes of routes, or of expected traffic, related to the choice of the corresponding a factors.

A value of Y2 other than zero may b® specified, for the UDL system of LM1 only, for bridges supporting a severe continuous traffic.

3) The factors for UDL apply not only to the distributed part of LM1, but also to the reduced pedestrian load mentioned in Table 4.4.

4) When the wind action is treated as the dominant action (i.e. represented by F^ or FWn), yg for gr1 should be taken as zero and the additional thickness specified in C.2.1.1(3) is not considered. When the traffic action is treated as dominant, the wind action vo^Wk or Vo^T/Vn should be taken as not greater than F^ (see C2.1.1(7)), and its representative value is calculated taking into account the additional thickness specified in C2.1.1 (3).

5) Unless otherwise specified (e.g. in the case of brittle materials at low temperature - see the relevant design Eurocode). However, for SLS, see C3.4(1).

C3 - Serviceability limit states

C3.1 Simultaneity of load models with other actions

(1) The rules concerning simultaneity given in C2.1.1 are applicable. C3.2 Combinations of actions

(1) For persistent and transient design situations the various combinations should be taken from ENV 1991 -1, 9.5.2.

(2) In addition, if specified by the design Eurocode, the infrequent combination:

j i>l should be considered. C3.3 Partial factors

(1) For road bridges, the partial factors on actions for Serviceability Limit States in persistent and transient situations should be taken as [1.0] unless otherwise specified.

C3.4 Y factors for road bridges

(1) Values of y factors are given in Table C.2, excepted the y0-value applicable to thermal effects, which is equal to I 0,6 |.

C4 - Fatigue

(1) The verification rules for fatigue depend on the Fatigue Load Model to be used and are specified in the design Eurocodes.

Basis of design - supplementary clauses to ENV 1991-1 for footbridges

Note : This annex is intended, at a later stage, to be incorporated into ENV 1991-1 "Basis of design".

(1) This annex gives rules on partial factors on actions (y-factors), and on combinations of pedestrians and cycle traffic loads on footbridges with permanent actions, quasi-static wind, snow and temperature actions, and the relevant y-factors. If other actions need to be considered (e.g. mining subsidence, instability due to wind, water, floating debris and ice pressure for some verifications relating to foundations), the combinations should be supplemented to take them into account. This annex should also be supplemented and adapted for the erection phases (see the relevant design Eurocodes) and for some particular categories of footbridges (e.g. moving footbridges).

(2)P Footbridges are categorized as :

- those on which pedestrian - and cycle traffic is not protected, or not fully protected, from all types of bad weather, and

- those on which traffic is fully protected.

D2 - Ultimate limit states D2.1 Simultaneity of load models D2.1.1 Models of variable actions

(1) When relevant, the vertical loads and horizontal forces due to traffic shall be considered as simultaneous in accordance with clauses 5.3 and 5.4 and taken into account as groups of loads. Characteristic values of these loads are given in Table D.1. For other representative values they are modified and generally simplified by introducing the relevant y factors.

Table D.1 - Definition of groups of loads (Characteristic values)

Load type |
Vertical forces |
Horizontal forces | ||

Load system |
Uniformly Distributed Load |
Service Vehicle |
Was this article helpful? |

## Post a comment