Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 391

l 1 ¼ 93 : 9 0 : 924 ¼ 86 : 7636

2343
24

1

l¼

7636 ¼ 1

: 111

: 3 86 :

The axial compressive force in the diagonal bracing member
( N Ed ¼ 86.8 kN):

N Ed

N b , Rd 1

: 0

wAf y
g M1

where N b , Rd ¼

6cm 2 A¼ 2 12 : 3 ¼ 24 :

1
F +

w¼ p but w 1 : 0

l 2 F 2

h i

+ l 2

51+ a l 0 F¼ 0 : : 2

¼ 1

111 2 F¼ 0 : 51+0 : 34 1 ð : 111 0 : 2 Þ +1 : : 272

1

w¼

272 +

p ¼ 0 : 529 w 1 : 0

272 2 111 2

1 : 1 : 1 :

0 : 529 24 : 6 100 275

1

Then, N b , Rd ¼ ¼ 325,335N

: 1

N b , Rd ¼ 325 : 3kN > N Ed ¼ 86 : 8 kN Then O ð : K : Þ

4.5.9 Design of Wind Bracings
Wind forces acting on the double-track railway bridge (see Figure 4.152 ) as
well as any other lateral forces directly applied to the bridge are transmitted
to the bearings by systems of wind bracing. For pony bridges, only the lower
wind bracing carries wind forces on the moving train, wind forces on the
main plate girder, and lateral shock (nosing force) applied to the tracks
(see Figure 4.153 ). Wind forces applied to this bridge can be sufficiently esti-
mated 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

53m 2 A ref , x ¼ 4 : 9118 28 ¼ 137 :