Applied Loads and Stability of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 217

the thickness of the roller plates, the following shall be satisfied using the load
distribution shown in Figure 3.48 under the fundamental combination of
actions:

N Sd N Rd ð 3 : 134 Þ

N Rk
g m

where N Rd ¼ ð 3 : 135 Þ

L

and N Rk ¼ f y 2 t p + b ð 3 : 136 Þ

where b can be calculated according to Hertzian stress analysis principles or
taken as equal to 0, L is the effective length of roller (mm), and g m ¼ 1.1.
BS EN 1337-4 [ 3.12 ] specifies that for roller bearings, the stiffness of the
supporting plates is of paramount importance; therefore, the roller plates
shall be so proportioned that loads are adequately distributed to adjacent
components ( Figure 3.47 ) . The maximum load dispersion through a com-
ponent shall be taken as 45 unless a greater angle is justified by calculations
that take into account the characteristics of the adjacent components and
materials. In no case shall load dispersion be assumed beyond a line drawn
at 60 to the vertical axis (see Figure 3.48 ). Where movement requirements
permit, flat-sided rollers may be used. Such rollers shall be symmetrical about
the vertical plane passing through the axis of the roller. The minimumwidth
shall not be less than one-third of the diameter nor such that the bearing con-
tact area falls outside the middle third of the rolling surface when the roller is

Normal force

Horizontal force

Roller plate

Roller
Roller plate

(a) Single roller bearing

(b) Flat-sided roller bearing

Figure 3.47 Cylindrical and flat-sided roller bearings.