Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 240

C 1 ¼ 284mm, t fl ¼ 30, C 1 = t fl ¼ 284 = 30 ¼ 9 : 47 14 0 : 924

¼ 12 : 94 Class 3 ð Þ:

C 2 ¼ 2984mm, t w ¼ 16, C 1 = t fl ¼ 2984 = 16 ¼ 186 : 5 > 124 0 : 924

¼ 114 : 58 Class 4 ð Þ:

To calculate the bending moment resistance, the effective area should be
used. Considering web plate buckling, the effective area of the part of web
plate in compression (see Figure 4.18 ) can be calculated as follows:
k s ¼ 23 :

9

300 = 1 : 6

l p ¼

p

23

¼ 1 : 462 > 0 : 673

28 : 4 0 : 924 : 9

1 : 462 0 : 055 3 1 ð Þ

r¼ ¼ 0 : 633

462 2 1 :

b eff ¼ 0 : 633 300 = 2 ¼ 95 cm,

Then, b eff1 ¼ 0.6 95 ¼ 57 cm and b eff2 ¼ 0.4 95 ¼ 38 cm as shown in
Figure 4.18 .
To calculate the elastic section modulus, the elastic centroid of the sec-
tion has to be located by taking the first area moment, as an example, around
axis y 0 - y 0 shown in Figure 4.18 , as follows:

6 ¼ 752 cm 2 A¼ 60 3 2 + 245 1 :

½ 60 3 1 : 5 + 207 1 : 6 106 : 5+38 1 : 6 284 + 60 3 304 : 5

y c ¼

752

y c ¼ 143 : 1cm

Inertia about y 1 - y 1 ¼ 60 3 3 6 2 ½ = 12 + 60 3 141 :

+60 3 3 4 2

½ = 12 + 60 3 161 :

:

6 207 3 6 2

+1 ½ = 12 + 1 : 6 207 36 :

6 38 3 9 2 +1 ½ : = 12 + 1 : 6 38 140 :

4cm 4

¼ 11,139,025 :

5cm 3

W eff , min ¼ 11,139,025 : 4 = 162 : 9 ¼ 68,379 :