Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 249

R A R B

30 m

A s

B

a s

Fsin a F

q WL = 23.27 kN/m

100 kN

Figure 4.26 Loads on the upper wind bracing.

wind forces on upper half of the main plate girder, and lateral shock (nosing
force) applied to the tracks (see Figure 4.26 ) . On the other hand, wind forces
acting on the lower half of the main plate girder are transmitted by the lower
wind bracing (see Figure 4.27 ) . Wind bracings are quite important to the
lateral stability of the bridges, and therefore, it is recommended to use iden-
tical cross sections for the upper and lower wind bracings. Wind forces
applied to this bridge can be sufficiently estimated using the design rules
specified in EC1 [3.2] as follows:

1

2 rv b CA ref , x
v b ¼ c dir c season v b , 0 ¼ 1

F w ¼

: 0 1 : 0 26 ¼ 26m = s

A ref , x ¼ 7 31 ¼ 217m 2

1
2 1

25 26 2 F w ¼ : 5 : 7 217 ¼ 522,590 : 3N ¼ 522 : 6kN

R A R B

30 m

B

A

3.6 m

7.2 m

3.6 m

q WL = 6.34 kN/m

Figure 4.27 Loads on the lower wind bracing.