Evaluation of Load Distribution Factors on AASHTO LRFD Design Parameters of the Bridges Deck by Harmonic Analysis

Abstract

Load distribution factors have a substantial role in the analysis and design of highway bridges. In this research, the effect of load distribution factors on the design parameters of bridge superstructures are studied by a numerical semi-continuum method. Three different case studies are carried out in the research to compare the accuracy and performance of the method. The objective of the first case is to control the outcomes of the method with the results of finite element method as well as AASHTO LRFD method. The second case is presented to study the effect of design parameters on load distribution factors between longitudinal girders through the three methods. Finally, a field test investigation is studied in the last case to compare all three methods with an actual field test study. It has been shown that the AASHTO LRFD method is not precise enough in comparison with the present method. The AASHTO LRFD formulas for live load distribution are quite unreliable and can give design parameters far too low or far too high. Moreover, minimum calculation time, convenient performance and high accuracy in the solution process are the other advantages of the method proposed in this research.