Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 426

s

a

F sin a

4 m

D 2

B

A b

s

5 m 30 m

5 m

g vk = 77.1 kN/m

450 kN

450 kN

q vk = 45.65 kN/m

450 kN 450 kN

1.2 m

q vk = 45.6 5 kN/m

1.2 m 1.6

0.2

0.152

+

-

1.152

1.6 1.2

4.29 m

0.71 m

Figure 4.187 Determination of the force in diagonal member D 2 using the influence
line method.

F L : L : D ðÞ positive ð Þ 450 0 ð : 2+0 : 152 Þ +0 : 57 45 : 65 + 20 : 57

2 : 45 + 7 : 5 1 ð : 2+1 : 152 Þ ¼ 252 : 5kN

F Ed D ð maximum ¼F D : L : g g + F L : L : g q

F Ed D ð maximum ¼ 1542 1 : 3 2001 : 5 1 : 35

¼ 4706 : 6 kN Compression force ð Þ

F Ed D ð minimum ¼F D : L : g g + F L : L : g q

F Ed D ð minimum ¼ 1542 1 35

¼ 1663 : 7 kN Compression force

: 3 + 252 : 5 1 :

ð Þ

4.6.3.9 Calculation of Force in the Diagonal Chord Member D 1
The force in the diagonal truss member D 1 can be calculated, as shown in
Figure 4.188 , as follows:
A +ve D ðÞ¼ 0 :

5 40 1

:

4 ¼ 28

F D : L : D ðÞ¼ 28 77 : 1 ¼ 2158 : 8kN