Approximate Analysis of Irregular Slab-on-Girder Bridges

Abstract

A simple, approximate method for determining the live-load girder distribution factors of irregular slab on I-beam bridge layouts is presented. The method can also be used for the live-load analysis of bridges subjected to one truck, as in the case of fatigue, or two (or more) different truck configurations, as in the case of permit loading. The method takes into account the longitudinal as well as transverse effects of the truck loads. It is based on isolating strips of the deck slab in the transverse direction directly under the wheel loads and treating them as beams on elastic supports. The stiffness of the supports at the strip locations is computed based on the geometric properties of the beams and location of the trucks in the longitudinal direction. The accuracy of the method for shear and flexure of I-beams in simple and continuous span bridges is verified using a detailed three-dimensional finite-element analysis.