Abstract

The load effects to which bridge systems and structural elements are subjected to due to vehicular passage are estimated using live load models contained in bridge design codes. Those live load models are frequently derived for girder bridges subjected to shear forces and bending moments. However, other type of bridges, as truss bridges and others, can be subjected to other forces too, for instance axial loads and other effects. In Mexico, in past decades 3D-truss bridges based on a structural system known as “Tridilosa” were designed and built. The live load models to analyze them were widely used to design girder bridges; moreover, the traffic at the time may differ from more recent trucks and vehicles. This paper investigates the adequacy of live load models from codified design to represent load forces on the referred 3D-truss bridges, as compared to realistic Mexican traffic from WIM (weigh-in-motion) data. The results show that live load models in bridge codes are not necessarily adequate to assess forces in the existing 3D-truss (“Tridilosa”) bridges in Mexico.