For any combination of traffic loads together with actions specified in other Parts of ENV 1991, any such group should be considered as one action.

The characteristic wind action on footbridges may be assessed in ENV 1991-2-4 either as characteristic force F^ or as norminal force FWn.

(2)P The forces and constrained deformations resulting from relevant permanent and variable actions on bridges specified in other Parts of ENV 1991 shall be considered simultaneously in combinations with the traffic loads where relevant.

(3) The concentrated load Qfwk (see 5.3.2.(4)) should not be combined with any other variable non-traffic load.

(4) For footbridges, wind and thermal actions should not be taken into account as simultaneous.

(5) For the first category of footbridges defined in D1.(2)P, the traffic may be considered to be incompatible with significant wind and/or snow, unless otherwise specified.

(6) For the second category of footbridges defined in D1 .(2)P, the fundamental combinations are the same as for buildings, unless otherwise specified (see ENV 1991-1), the imposed loads being replaced by the relevant group of loads, the partial factors on actions and the vo factors being applied in accordance with the design Eurocodes, and the other y factors for traffic actions being in accordance with D.2.4.

Note : This implies in principle at least four combinations, each of them including four variable actions with a series of load cases. It is recommended that the possibilities of simplifications be examined for particular projects.

D2.1.2 Models including accidental actions

(1) Where an accidental action is to be considered, no other accidental action or wind or snow actions should be considered to occur simultaneously.

(2) The simultaneity of accidental actions with variable traffic actions is defined below and where the relevant individual accidental actions are defined.

(3) When collisions due to traffic running under the bridges are considered (see 5.6.1 and 5.6.2), the frequent loads due to the traffic running on the bridges should be introduced as accompanying actions in the combinations, unless otherwise specified.

(4) When accidental actions due to the traffic running on bridges are considered (loads defined in 5.6.3), all accompanying traffic actions should be neglected, unless otherwise specified.

Note : When other accidental actions on bridges have to be considered, rules on simultaneity with traffic actions shall be specified.

D2.2 Combinations of actions

(1)P For each critical load case, the design values of the effects of actions shall be determined by combining the values of actions which occur simultaneously. ENV 1991-1,9.4.2 applies.

D2.3 Partial factors for footbridges

(1) The partial factors on actions for Ultimate Limit States in the persistent, transient and accidental design situations are the same as specified in annex C (C.2.3).

D2.4 Y factors for footbridges

(1) Unless otherwise specified (eg. in the relevant Part of ENV 1991 devoted to specific actions), y factors for the first category of footbridges are as given in Table D.2. For the second category, see D.2.1.1(6) above. For traffic action, in both cases, the factors apply as well to the groups of loads defined in Table D.1 as to the individual components of the groups where they are considered separately.

Table D.2 - v factors for footbridges





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