Applied Loads and Stability of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 150

unfavorable parts of the influence surface, longitudinally and transversally.
The characteristic value of the concentrated load Q fwk should be taken equal
to 10 kN acting on a square surface of side 0.10 m. Finally, when service
vehicles are to be carried on a footbridge or footway, one service vehicle
Q serv shall be taken into account. This vehicle may be a vehicle for main-
tenance, emergencies (e.g., ambulance and fire), or other services. The char-
acteristics of this vehicle (axle weight and spacing and contact area of
wheels), the dynamic amplification, and all other appropriate loading rules
may be defined for the individual bridge.
The horizontal forces for footbridges are also specified in EC1. A hor-
izontal force Q flk should be taken into account, acting along the bridge deck
axis at the pavement level, as defined in EC1. The characteristic value of the
horizontal force should be taken equal to the greater than 10 percent of the
total load corresponding to the uniformly distributed load and 60 percent of
the total weight of the service vehicle. The horizontal force is considered as
acting simultaneously with the corresponding vertical load and in no case
with the concentrated load Q fwk . EC1 states that this force is normally suf-
ficient to ensure the horizontal longitudinal stability of footbridges. It does
not ensure horizontal transverse stability, which should be ensured by con-
sidering other actions or by appropriate design measures. Accidental design
situations for footbridges are also covered by EC1. Such situations are due to
road traffic under the bridge (i.e., collision) or the accidental presence of a
heavy vehicle on the bridge. Dynamic models of pedestrian loads are also
specified in EC1.
3.5.5 Thermally Induced Loads
Temperature changes in bridges and their accompanied forces induced on
the bridges are covered by EC1 (BS EN 1991-5) [ 3.3 ] . For the purposes
of this part, steel and steel-concrete composite bridge decks are grouped into
three types. Type 1 comprises steel bridges with steel decks supported by
steel box girder or steel truss or plate girder main structural supporting sys-
tems ( Figure 3.19 ). Type 2 comprises bridges with composite decks. Type 3
comprises bridges with concrete decks. Representative values of thermal
actions should be assessed by the uniform temperature component and
the temperature difference component. Where a horizontal temperature dif-
ference needs to be considered, a linear temperature difference component
may be assumed in the absence of other information. The uniform temper-
ature component depends on the minimum and maximum temperature that