Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 286

F Ed D ð minimum ¼F D : L : g g + F L : L : g q
F Ed D ð minimum ¼ 1501 :

1 1

:

3 274

:

5 1

:

35

¼ 1580 : 9 kN Tension force ð Þ

It should be noted that, from the equilibrium of joint J 3 (see Figure 4.62 ),
the force in the vertical truss member V 3 is equal to that of D 3 multi-
plied by sin a but with a negative sign (a compression force of
4086.1 sin 51.34 ¼ 3190.7 kN).

4.3.3.10 Calculation of Force in the Diagonal Chord Member D 2
The force in the diagonal truss member D 2 can be calculated, as shown in
Figure 4.63 , as follows:

A +ve D ðÞ¼ 0 : 5 53 : 33 1 : 025 ¼ 27 : 33

A ve D ðÞ¼ 0 : 5 6 : 67 0 : 128 ¼ 0 : 427

A net D ðÞ¼ 27 : 33 0 : 427 ¼ 26 : 9

s

a

D 2

V 2

7.5

F sin a

B

b

s

A

6 m

6 m

48 m

g vk = 78.1 kN/m

375 kN

375 kN

q vk = 43.8 kN/m

375 kN

375 kN

1.2 m

q vk = 43. 8 kN/m

1.281

1.2 m

0.128

0.102

-

+

1.025

0.999

1.281

5.33 m

0.67 m

Figure 4.63 Determination of the force in diagonal member D 2 using the influence line
method.