# Parametric Study of Fatigue Load Models for Highway Bridges

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Effect of parameters on bending moment and shear force The study compares the effect of parameters on bending moment and shear force produced by fatigue load models. The fatigue load models are again classified based on number of axles for the calculation of bending moment and shear force. The bending moment and shear force is calculated for simply supported span. Bridge span is adopted as variable. The maximum bending moment and shear force is calculated to study the effect on bending moment and shear force with increase in span. Effect of number of axles on bending moment and shear force Bending moment and shear force decreases as number of axles increases, because with increase in number of axles the distribution of load increases. For instance, for almost same gross vehicle weight and 50 m span: in Figure 14, Euro code two axle FLM 4 (GVW = 200 kN) and in Figure 16, three axle Schilling’s model (GVW = 222 kN) produces bending moment 2344 kN.m and 2283 kN.m respectively; in Figure 16, Euro code three axle FLM 4 (GVW = 310 kN) and in Figure 18, four axle BS 5400 model (GVW = 320 kN) produces bending moment 4239 kN.m and 3374 kN.m respectively; in Figure 18, four axle Laman’s model (GVW = 490 kN) and in Figure 20, Euro code five axle FLM 4 (GVW = 490 kN) produces bending moment 5280 kN.m and 5265 kN.m respectively. In all the three examples, the models of same gross vehicle weights are compared to see the effect of increase in number of axle and the reduction in bending moment is seen in all the three cases. Effect of gross vehicle weight on bending moment and shear force Bending moment and shear force increases with increase in gross vehicle weight. For instance, for 50 m span: in Figure 14, Bing and Wu’s fatigue load model ha... ... middle of paper ... ...of city bridges.” Second International Conference on Intelligent Computation Technology and Automation, 41–44. 3. Bowman, M. D. and Chotickai, P. (2006). “Truck models for improved fatigue life predictions of steel bridges.” Journal of Bridge Engineering, ASCE, Vol.11, S.No.1, 71–80. 4. BS 5400 part 10 (1980), “Steel, concrete and composite bridges, Part 10.” Code of practice, British standard Institution. 5. BS EN 1991-2 (2003) “Euro code 1 - Actions on structures - Part 2: Traffic loads on bridges.” European Committee for Standardization, Brussels. 6. Laman, J. A. and Nowak, A. S. (1996) “Fatigue load models for girder bridges.” Journal of Structural Engineering, ASCE, Vol.122, S.No.7, 726-733. 7. Schilling, C.G. and Klippstein, K.H. (1977). “Fatigue of steel beams by simulated bridge traffic.” Journal of the Structural division, ASCE, Vol.103, S.No.8, 1561-1575.