Introduction - Computational Analysis and Design of Bridge Structures - page 10

Figure 1.8 The schematic view of a truck on the Middlebrook Bridge finite element model.

collision, have also to be considered in the design process. Definitions of live
loads used for bridge designs are different from one specification to another,
and usually they are subjected to be amended when traffic demands change
years later. For example, HL-93 as shown in Figure 1.9a and b, which is cur-
rently used in the U.S. bridge design, specifies two different vehicular loads
combined with a lane load, and the extreme values should be taken as the
maximum of these two combinations. After 2004, a more simplified live load
definition was adopted in China's highway bridge designs, in which one class
of live load, for example, class I as shown in Figure 1.10a and b, contains
lane load and one single vehicle load, and the extreme values should be taken

32 kips
(145 kN)

32 kips
(145 kN)

8 kips
(35 kN)

14-30 ft
(4.3-9.0 m)

14 ft

(4.3 m)

q = 0.64 kips/ft
(9.3 kN/M)

(a)

4 ft
(1.2 m)

25 kips
(110 kN)

25 kips
(110 kN)

q = 0.64 kips/ft
(9.3 kN/M)

(b)

Figure 1.9 U.S. bridge design live loads (US HL-93). (a) Design truck and design lane;
(b) design tandem and design lane.