(2) For bridges carrying track having an expansion device at both ends of the deck:
184.108.40.206 Longitudinal actions due to deflection of the structure
(1)P The bridges for which these actions are to be calculated shall be specified. The effects of traffic action shall be considered at each bearing separately and particular calculation shall be carried out for each structure.
Note: The bridges to take into consideration shall be specified in agreement with the relevant authority.
6.6 Slipstream effects from passing trains (aerodynamic effects)
(1) The passing of rail traffic subjects any structure situated near the track to a travelling wave of alternating pressure and suction (see Figure 6.13 and Figure 6.14).
The magnitude of the action depends mainly on
(a) the square of the speed of the train,
(b) the aerodynamic shape of the train,
(c) the shape of the structure,
(d) the position, particularly the distance of the structure from the track.
(2) The actions may be approximated by equivalent loads at the head and rear end of the train, when checking ultimate limit states and fatigue.
(3) The equivalent loads are considered to be characteristic values of the actions.
6.6.2 Simple vertical surfaces parallel to the track
(e.g. noise barriers)
(1)P The characteristic values of the actions, ± qr1k, are given in Figure 6.13. section plon view
(2) The characteristic values apply to trains with an unfavourable aerodynamic shape and may be reduced by:
- a factor /c, = 0,85 for trains with smooth sided rolling stock
- a factor /cn = 0,6 for streamlined rolling stock (e.g. ETR, ICE, TGV)
(3)P If the height of a structural member (or part of its influence area) is less than or equal to 1,00 m or if the width is less than or equal to 2,50 m, the actions g1k are to be increased by a factor k2 = 1,3.
6.6.3 Simple horizontal surfaces above the track
(e.g. overhead protective structures)
(1)P The characteristic values of the actions, ± g2k, are given in Figure 6.14.
(2)P The loaded width for the structural member under investigation extends up to 10 m to either side from the centre-line of the track.
section elevotion underside of the structure underside of the structure
(3)P For trains passing each other in opposite directions the actions shall be added. Only two tracks need to be considered.
(4) The actions qr2k may be reduced by the factor /c, as defined in 6.6.2.
(5) The actions acting on edge strips which cross the track may be reduced by a factor of 0,75 over a width up to 1,50 m.
6.6.4 Simple horizontal surfaces adjacent to the track
(e.g. platform canopies)
(1)P The characteristic values of the actions, ± g3k, are given in Figure 6.15 and apply irrespective of the aerodynamic shape of the train.
(2)P For every position along the surfaces to be designed, q3k shall be determined as a function of the distance ag from the nearest track. The actions shall be added, if there are tracks on either side of the structural member under consideration.
(3) If the distance h9 exceeds 3,80 m the action qr3k may be reduced by a factor k3: (7,5-hg)
hg distance from top of rail level to the underside of the structure q 3k[kN/m2] section
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