Contribution of Intermediate Diaphragms in Enhancing Precast Bridge Girder Performance

Abstract

The objective of this study was to determine the effect of intermediate diaphragms on the stiffness of precast prestressed AASHTO type bridge girders, combined with the actual bearing stiffness and thermal changes. Some of the parameters studied include the presence of intermediate diaphragms, bridge skewness, temperature change, and an increase in bearing stiffness due to cold temperature or aging. A finite element model of a bridge superstructure containing Florida Bulb Tee 78 girders was created. This model was subjected to an HL93 truck load as suggested by the AASHTO LRFD. Results indicate that intermediate diaphragms have a modest positive effect of reducing the maximum deflections for the chosen girder, with the effect varying with skewness and thermal change.