Design Examples of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 452

movement in the direction of rollers. The thickness of the upper bearing
plate can be determined as follows:

9 10 3
700 800

R D+L+ F 4433 :

f c ¼

a 3 b 3 ¼

f c 40

1

f c 40

1

¼ 7 : 92MPa <

g c ¼ 5 ¼ 26

: 7MPa <

g c ¼ 5 ¼ 26

: 7MPa

: :

(for a typical concrete in bridges of C40/50 with f ck )
The plate thickness t 3 can be calculated from the distribution of bending
moment, caused by the pressure on the concrete foundation, as follows:
M¼ 183, 051Nmm 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

183,051
0

340
1 25 t 3 ¼ 0

Then, t 3 ¼ 46.4 mm, taken as 50 mm, as shown in Figure 4.209 .

: :

4.6.3.26 Design of Hinged Line Rocker Steel Fabricated Bearings
Finally, we can now design the hinged line rocker steel fabricated bearings
shown in Figure 4.162 and detailed in Figure 4.210 . The maximum ver-
tical reaction at the support of the main plate girder was previously calcu-
lated under dead and live loads with dynamic effect ( R D+L+ F ), which was
4433.9 kN. The bearing is also subjected to a lateral force from the braking
forces from traffic as well as subjected to a longitudinal force from the reac-
tions 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 ulti-
mate stress of 550 MPa. It should be noted that the overall 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 bear-
ing are shown in Figure 4.211 . Thebraking Q lbk forces can be calculated as
follows:
Q lbk ¼ 360 + 2 : 7 L ¼ 360 + 2 : 7 40 ¼ 468 kN, for Load model 1