FINITE ELEMENT ANALYSIS OF CONCRETE CURVED BOX GIRDER BRIDGES

Abstract

Reinforced concrete single or multicell box girder bridges appear at present to be the most popular construction for curved highway bridges. The analysis of a curved box girder having single or multicell gets complicated due to deformability of the cross section and the arbitrariness of the applied loads. Box- girder sections are most suitable for highway bridges curved-in-plan, because of its certain structural advantages;-particularly when the span is large and/or radius of curvature is small. Single cell box girder with overhanging top flange and vertical or inclined webs is the most popular cross-section for concrete bridges, and is widely used in medium span range. The present project has been undertaken with the purpose of studying the behaviour of box girder bridges curved in plan under IRC recommended loads. The finite element software ANSYS has been used for the analysis purpose. Generally, the angle of curvature of a horizontally curved highway bridge is less than 20 degrees. Unlike the straight bridges the curved bridges pose greater problem in determining the influence lines and hence in arriving at the critical positions of the live loads for any stress resultant. Often, therefore, the trail and error procedure is adopted for the analysis of curved box girder bridges wherein the loads are placed nearby the positions for a straight bridge having the same span. In the present work the angle of curvature of the bridge span has been kept 20 degrees and the span/depth ratio has been varied. The JRC recommended loads have been applied and the deflection, longitudinal stress and transverse moment diagrams have been plotted.