Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 375

Dead Loads

Weight of steel structure ¼ 11 + 0

:

5 27 ¼ 24

: =

5kN m

Track load ¼ 6kN = m

m
The main plate girders are simply supported; hence, we can calculate the
maximum shear force and bending moment due to dead loads on a main
plate girder (see Figure 4.138 ) as follows:
Q D : L : ¼ g vk L

Total dead load ¼ g vk ¼ 1 : 8 24 : 5 = 2+6 ¼ 28 : 05 kN =

= 2 ¼ 28 : 05 27 = 2 ¼ 378 : 7kN

M D : L : ¼ g vk L 2 05 27 2

= 8 ¼ 28 : = 8 ¼ 2556 : 1kNm

Live Loads
Considering the axle loads on the bridge components according to Load
Model 71 (see Figure 4.129 ) , two cases of loading for the evaluation of max-
imum bending moment due to live loads on a main plate girder can be stud-
ied. The first case of loading is that the centerline of the main plate girder is
located under one of the intermediate concentrated live loads, with maxi-
mum bending moment calculated at midspan (see Figure 4.139 ) . On the
other hand, the second case of loading is that the centerline of a main plate
girder divides the spacing between the resultant of the concentrated live

g vk = 28.05

A

B

27.0 m

Y A = 378.7 kN

Y B = 378.7 kN

378.7 kN

+

S.F.D.

-

378.7 kN

B.M.D.

+

2556.1 kN m

Figure 4.138 Straining actions from dead loads acting on one main plate girder.