Jl

Figure 6.15: Characteristic values of actions g,k for simple horizontal surfaces adjacent to the track

6.6.5 Multiple-surface structures alongside the track with vertical and horizontal or inclined surfaces

(e.g. bent noise barriers, platform canopies with obstructions)

(1)P The characteristic values of the actions, ± q4k, as given in Figure 6.16 shall be applied normal to the surfaces considered. The actions are to be taken from the graphs in Figure 6.13 adopting a fictitious track distance of a'g = 0,6 min ag + 0,4 max ag * 6 m where:

distances min ag max a8 shown in Figure 6.16.

(2)P If max a9 > 6 m the value max ag = 6 m shall be used.

(3)P The factors ky and k2 as in 6.6.2 shall be used.

tci4k(iqik)

max oq sPik>

Figure 6.16: Definition of the distances min ag and max ag from centre-line of the track

6.6.6 Surfaces enclosing the structure gauge of the tracks over a limited length (15-20 m)

(horizontal surface above the tracks and at least one vertical wall, e.g. scaffolding, temporary constructions)

(1 )P All actions shall be applied irrespective of the aerodynamic shape of the train:

- to the full height of the vertical surfaces:

where:

Q1k is determined according to 6.6.2, k4-2

- to the horizontal surfaces: ±*5<72k

where:

q2k is determined according to 6.6.3, ks = 2.5 if one track is enclosed = 3.5 if two tracks are enclosed

6.7 Accidental actions

6.7.1 Accidental actions from railway traffic

6.7.1.1 Derailment on or under bridges

(1)P Railway structures shall be designed in such a way that, in the event of a derailment, the resulting damage to the bridge is limited to a minimum. In particular, overturning or the collapse of the structure as a whole shall be prevented.

6.7.1.2 Derailment on bridges: structural requirements and equivalent loads

(1)P Two design situations shall be considered:

Design situation I: Derailment of locomotive or heavy freight wagons, with the derailed vehicles remaining in the track area on the bridge deck.

Design situation II: Derailment of locomotive or heavy wagons, with the derailed vehicles remaining in the track area without falling off the bridge, but remaining balanced on its edge.

(2)P For determining the requirements and equivalent loads for design situation I, collapse of a major part of the structure shall be avoided. Local damage, however, is tolerated. The parts of the structure concerned shall be designed for the following equivalent loads at the ultimate limit state:

Two vertical line loads with a design value of gA1d= 50 kN/m each over a length of 6,40 m and 1,40 m apart, parallel to the track in the most unfavourable position inside an area of width 1,5 times the gauge on either side of the track centre-line;

max.l,5s

Was this article helpful?

0 0

Post a comment