Stability of steel girders under the effect of temperature variations and moving loads in integral abutment bridges

Abstract

The response of a three-span integral abutment bridge to environmental conditions and traffic loads was evaluated through field monitoring and detailed three-dimensional finite element (FE) modelling. The field-measured data indicate that axial compressive stresses developed in steel girders due to constrained expansion during summer may affect the stability of the steel girders. The FE model was used to investigate the bridge response under the effect of dead load, temperature variations as well as live load. The FE-calculated lateral deformation of the steel girders was used to determine the effective length factor k_b, which was found to be much less than the AASHTO recommended value. Using the 3D FE-calculated effective length factor, the calculation of the stability ratio under identical loading conditions was found to satisfy the AASHTO criteria, leading to the conclusion that the AASHTO standards are overly conservative. This raises the need for more accurate solutions to predict lateral buckling behaviour of composite I girders.