Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 295

L cr
i

1
l 1

l¼

l 1 ¼ 93 : 9 0 : 924 ¼ 86 : 7636

6000
170

1

l¼

7 7636 ¼ 0

: 41

: 86 :

The axial compressive force in the upper chord member U 3
( N Ed ¼ 7449.1 kN):

N Ed
N b , Rd 1

: 0

wAf y
g M1

where N b , Rd ¼

1
F +

w¼ p but w 1 : 0

l 2 F 2

h i

+ l 2

51+ a l 0

F¼ 0 : : 2

¼ 0

41 2 F¼ 0 : 51+0 : 34 0 ð : 41 0 : 2 Þ +0 : : 62

1
0 : 62 +

w¼ p ¼ 0 : 922 but w 1 : 0

0 : 62 2

41 2

0 :

0 : 922 37200 275

1

Then, N b , Rd ¼ ¼ 8,574,600N

: 1

N b , Rd ¼ 8574 : 6kN > N Ed ¼ 7449 : 1 kN Then O ð : K : Þ

4.3.3.16 Design of the Compression Upper Chord Member U 1
The compression member U 1 , shown in Figure 4.70 , carrying a compressive
design force of 4191.2 kN can be designed as follows. To classify the cross
section chosen (see Figure 4.70 ) ,

s

235
f y

r

235
275

e ¼ ¼ ¼ 0 : 924

b ¼ 400mm, t fl ¼ 12, b = t fl ¼ 400 = 12 ¼ 33 : 3 < 35 : 11 Flange is Class 2 ð Þ

C ¼ 414mm, t w ¼ 12, C = t fl ¼ 414 =

12 ¼ 34

: < : ð Þ

5 35 11 Web is class 2

2 ¼ 222 cm 2

A¼ 55 1 : 2+40 1 : 2+2 45 1 :