| The live load distribution factors (LDF) provided by AASHTO-LRFD Bridge Design Specification have been in effect for almost 20 years to calculate bending moment and shear force for highway bridge design. These equations are calibrated based on elastic finite element analysis. Maximum bending moments and shear forces are determined by the load distribution factors. Load distribution factors estimated by the LRFD equations are generally conservative compared with refined analysis results. The use of the AASHTO LRFD equations may not provide accurate load distribution factors for light rail bridges because the load configurations of light rail trains are different from those of highway vehicles. This study examines live load distribution factors for light rail bridges and proposes new equations.;For this study, standard light rail trains are placed on five different types of light rail bridges in Denver, Colorado. The focus of this thesis is on developing live load distribution factor equations for light rail bridges. The behavior of these light rail bridges subjected to 2", 4" and 6" substructure settlements is also studied.;In this study, 155 light rail bridges are designed and modeled. The load is applied to the five types of light rail bridges. The moment and shear of each bridge are predicted. This iv research proposes thirty-five new equations for five different types of light rail bridges for bending and shear, including interior and exterior girders. The distribution factors which have been calculated by the developed equations are compared with the AASHTO-LRFD distribution equations. Another comparison is also made against the responses of the constructed bridges. |
