Introduction - Computational Analysis and Design of Bridge Structures - page 11

41 to 81 kips
(180 to 360 kN)

q = 0 .72 kips/ft
(10 .5 kN/M)

(a)

31 kips
(140 kN)

31 kips
(140 kN)

27 kips
(120 kN)

27 kips
(120 kN)

7 kips
(120 kN)

4.6 ft
(1.4 m)

23 ft
(7.0 m)

4.6 ft
(1.4 m)

10 ft
(3.0 m)

(b)

Figure 1.10 China (highway class I) bridge design live loads. (a) Design lane; (b) design truck.

as the maximum of these two combinations (JTG D60-2004). In Europe,
Eurocode (EN 1991-2) defines traffic load models for road bridges as LM1-4,
where load model 1 (LM1 shown in Figure 1.11a) and load model 2 (LM2
shown in Figure 1.11b) are considered normal loads. Ontario highway bridge
design code (OHBDC 1991), similar to the AASHTO code, is using the maxi-
mum of two loads, truck load (Figure 1.12a) and lane load (Figure 1.12b). In
live load applications, various dynamic impact amplification factors, discount
due to multiple lanes and load factors, should be employed according to their
respective specific design codes. For further study of the live load effect of
various codes, refer to Bridge Loads: An International Perspective (O'Connor
and Shaw 2000). Bridge load rating, other than the bridge design, is a proce-
dure to evaluate the adequacy of various structural components of an existing
bridge to carry predetermined live loads (Jaramilla and Huo 2005).

Q 1 k = 67.4 kips
(300 kN)
Q ik

Q 2 k = 45.0 kips
(200 kN)

Q 1 k = 22.5 kips
(100 kN)

Q ik

q ik = 0.12 kips/ft 2
(5.5 kN/M 2 )

(a)

90 kips (400 kN)

(b)

Figure 1.11 Eurocode bridge design live loads. (a) Load model 1 (LM1); (b) load
model 2 (LM2).