Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 234

250 250 250 250 kN

Case of loading 1

q vk = 80 kN/m

A

B

1.6 1.6 1.6 0.8 24.4

30.0 m

0.95

0.89

1.0 0.84 0.81

I.L. for
S.F.D.

Figure 4.15 Determination of the maximum shear force on one main plate girder due
to live loads using the influence line method (case of loading 1).

analytically using structural analysis. Hence, the bending moments due to live
loads can be calculated as follows:

M L : L : ð case of loading 1 Þ ¼ 250 2 6 ½ : 3+2 7 : 1 +2 80 0 : 5

11 : 8 5 : 9

¼ 12295 : 2kNm

M L : L : ð case of loading 2 Þ ¼ 1437 : 5 14 : 6 80 12 : 2 8 : 5 250 1 : 6

¼ 12291 : 5kNm

There is only a single case of loading for the live loads to produce a maxi-
mum shear force at the supports of a main plate girder, which is shown in
Figure 4.15 . Once again, we can use the influence line method to calculate
the maximum shear force due to this case of loading or analytically by taking
moment at support B and evaluate the reaction at A:

Q L : L : ¼ 1713 : 8kN

Dynamic Factor F

L F ¼ 30m

2 : 16

p

30

F 3 ¼

2 +0

: 73 ¼ 1 : 139, F 3 1 : 0 and 2 : 0 :

0 :

Bending Moment Due to Dead and Live Loads with Dynamic Effect
Added (M D+L+F )

M D+L+ F ¼M D : L : g g + FM L : L : g q
¼ 3105 1 : 2+1 : 139 12,295 : 2 1 : 45 ¼ 24,032 kNm