by
Department of Civil and
Environmental Engineering
The Pennsylvania State
University
Horizontally curved girders are very useful in bridge design today. Before the early 1970’s, bridges with horizontal curvature were constructed by a series of straight girders, which would mimic the curvature of the roadway. The use of curved girders has created new design and analysis problems and challenges. In addition to the direct shear and bending stresses present in straight girder construction, curved girders must also resist the torsion in the system. Research has been conducted on the behavior of curved girders, scaled models have been created, and finite element models have been constructed, all in an attempt to determine their behavior. Current design codes are based on this early research, but little field data of in-service bridges exists to support the current design criteria. The purpose of this study was to gather field data from in-service curved girder bridges to determine their behavior when subjected to a weighed truck and random truck traffic. Distribution factors were calculated for both bending and torsional moments, and the dynamic load allowance was also calculated to determine the effect of impact on the girders. Values were obtained for diaphragm forces and deflections. A grillage model of one of the bridges was also developed to determine if a simple model could be created that would accurately reproduce the recorded results. All experimentally derived values were compared to current code values in an attempt to validate the code. The major contribution of this study was the field data of in-service curved girder behavior. This study has found that the current AASHTO factors are more than adequate for both Dynamic Load Allowance and Moment Distribution, but may not represent the true behavior of the bridge.