Inconsistencies between the forces from code live load models and real traffic on truss bridges

Abstract

The forces acting on bridge structural elements caused by live loads are computed by live load models defined in design codes. In most cases, such live load models are defined by studies performed on girder bridges, where extreme values of shear forces and bending moment are intended to be predicted. This paper shows that when code live load models are applied to truss bridges, the estimated forces in some structural elements may not be representative of those caused by actual traffic. Three WIM (weigh-in-motion) databases, which are recorded on roads in Mexico, are used as real traffic data. The results suggest that current code live load models are not entirely adequate to estimate forces in structural elements of truss bridges.