Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 318

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
F +

w¼ p but w 1 : 0

l 2

F 2

h i

+ l 2

F¼ 0 : 51+ a l 0 : 2

¼ 3

13 2

F¼ 0 : : ð :

13 0

: Þ +2 : :

51+0 34 2 2 097

1

w¼

097 +

p ¼ 0 : 187 but w 1 : 0

097 2 13 2

3 : 3 : 2 :

0 : 187 86 : 4 100 275

1

Then, N b , Rd ¼ ¼ 403,920N

: 1

N b , Rd ¼ 403 : 9kN > N Ed ¼ 325 : 6 kN Then O ð : K : Þ

4.3.3.33 Design of Roller Steel Fabricated Bearings
Let us now design the roller steel fabricated bearings shown in Figure 4.36
and detailed in Figure 4.90 . The maximum vertical reaction at the supports
of the main truss was previously calculated under dead and live loads with
dynamic effect ( R D+L+ F ), which was 5822.2 kN. The material of construc-
tion for the bearings is cast iron steel (ISO 3755) 340-550 having a yield stress
of 340 MPa and an ultimate stress of 550 MPa.

Design of the Sole Plate
The reaction ( R D+L+ F ) can be assumed as two equal concentrated loads at
two points, which are the centers of gravity of half of the last vertical
member V 11 shown in Figure 4.90 . To determine the centers of gravity
(distance e ), we can take the first area moment around the axis z - z , shown
in Figure 4.90 , as follows:

2 27 : 5 5 13 : 75 + 30 5 2 : 5

e ¼

¼ 9 : 78 cm

425

Assuming that the thickness of the sole plate is t 1 , with detailed
dimensions shown in Figure 4.90 based on the lower chord member L 1