A Study on Determination of the Maximum Traffic Live Load Effects for Bridges

Recently it is reported in many countries including Korea that bridges are seriously damaged due to increasing volume of overloaded vehicles. Since the safety of bridges are highly related to the design load level and extreme effects induced by traffic loads during their lifetime, it is important to determine the design live load to properly represent the load effect of the current truck traffic. The live load effect depends on many parameters including the span length, truck weight, axle loads, axle configuration, headway distance, heavy vehicle proportion, position of the vehicle on the bridge, and number of vehicles on the bridge. The objective of the study is to determine maximum effects of vehicle loadings based on the survey data collected and to evaluate the current design code. Several citation data were collected and two cases are considered : single truck and two trucks on the bridge. The maximum traffic live load effects for simple span and two equal continuous span bridges were calculated. As a result of this study, the live load effect of the current design code is relatively low at short-span (about 10m) and at span length of bifurcation point of DB-24 truck load and DL-24 lane load. Also shear forces of simple span is relatively lower than bending moments.