Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 259

2 10 3
600 800 ¼ 6 : 93MPa <

R D+L+ F 3327 : f c 40

1

f c ¼

a 3 b 3 ¼ g c ¼ : 5

¼ 26 : 7 MPa for a typical concrete in bridges of C40 ð = 50 with f ck Þ

The plate thickness t 3 can be calculated from the distribution of
bending moment, caused by the pressure on the concrete foundation, as
follows:

M ¼ 112,266 N mm per unit width of the plate :

b 3 t 3 1 t 3

25 t 2 mm 3 W pl ¼

4 ¼ 4 ¼ 0

:

M
W pl ¼

f y
g M0

112,266
0

340
1 25 t 3 ¼

0
Then, t 3 ¼ 36.3 mm, taken as 40 mm, as shown in Figure 4.33 .

: :

4.2.14 Design of Hinged Line Rocker Steel Fabricated Bearings
Finally, we can now design the hinged line rocker steel fabricated bearings
shown in Figure 4.1 and detailed in Figure 4.34 . The maximum vertical
reaction at the support of the main plate girder was previously calculated
under dead and live loads with dynamic effect ( R D+L+ F ), which was
3327.2 kN. The bearing is also subjected to a lateral force from the braking
and traction forces from tracks as well as subjected to a longitudinal force
from the reactions of the upper and lower wind bracings, which cause
moments around longitudinal and lateral directions of the bearing base,
respectively. Similar to the roller bearing, the material of construction 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. It should be noted that the over-
all height of the hinged bearing must be exactly the same as that of the roller
bearing. The general layout and assumed dimensions of the hinged line
rocker bearing are shown in Figure 4.34 . It should be noted that the hinged
line rocker bearings may not be the best hinged bearings for use nowadays.
However, the main advantage of choosing this bearing is to illustrate for
readers the applied loads on hinged bearings and review of the fundamentals
of checking the stresses on hinged bearing. Steel fabricated bearings consist
of designed parts, which are the best for teaching purposes. The traction Q lak
and braking Q lbk forces can be calculated as follows: