Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 447

The cross section of the bracing member (see Figure 4.28 ) can be
determined as follows:

2 7070 ¼ 8484mm
Choose two angles back-to-back 150 150 15, with 10 mm gusset
plate between them:

l b x ¼ 7070mm, l b y ¼ 1 :

4cm 2 , A¼ 2 43 : 2 ¼ 86 : i x ¼ 4 : 59 cm, e ¼ 4 : 26 cm,

q

4

2

59 2 +4 i y ¼ : ð : 26 + 1 = 2 Þ ¼ 6 : 61 cm

r

235
275

e ¼ ¼ 0 : 924

L cr
i

1
l 1

l¼

l 1 ¼ 93 : 9 0 : 924 ¼ 86 : 7636

7070
45

1

l¼

7636 ¼ 1

: 775

: 9 86 :

The axial compressive force in the diagonal bracing member
( N Ed ¼ 267.3 kN):

N Ed
N b , Rd 1

: 0

wAf y
g M1

where N b , Rd ¼

4cm 2 A¼ 2 43 : 2 ¼ 86 :

1

w¼ p

F 2

but w 1 : 0

l 2

F +

h i

+ l 2

51+ a l 0 F¼ 0 : : 2

¼ 2

775 2 F¼ 0 : 51+0 : 34 1 ð : 775 0 : 2 Þ +1 : : 343

1

w¼

343 +

p ¼ 0 : 258 but w 1 : 0

343 2 775 2 2 : 2 : 1 :

0 : 258 86 : 4 100 275

1

Then, N b , Rd ¼ ¼ 557280N

: 1

N b , Rd ¼ 557 : 3kN > N Ed ¼ 267 : 3 kN ThenO ð : K : Þ