DYNAMIC ANALYSIS OF HORIZONTALLY CURVED BRIDGES

Abstract

Horizontally curved bridges are the most feasible options at complicated interchanges or river crossings where geometric restrictions and constraint of limited site space, make difficult the adoption of standard straight superstructures. Usually these bridges are of cellular crosssection so that high torsional moment can be well resisted economically. Contrary to straight bridges, a very limited documentation on the study of horizontally curved bridges has been available. In this paper a parametric comparison was made between straight bridge and different curved bridges and skew bridges. Then these bridges were analyzed for dead, modal and moving load cases. This was done in order to study difference in the results obtained between straight, curved and skewed bridges for dead and moving load cases. The modeling part of the both bridges was done by using SAP 2000 in which there is an option named bridge wizard by which modeling of the bridge can dine in a sequential order. - After analyzing for dead load case unlike straight bridge there is torsion in the curved and skew bridges along the length of the bridge as there is unsymmetrical mass distribution in curved bridge about horizontal axis. While for the remaining dead and load cases the variation of axial force, vertical shear bending moment seems to be similar with an increase in magnitudes for curved bridge except for the axial force it was the other way around. Modal analysis showed the curved and skewed bridges have more initial torsional modes but whereas for straight bridge the initial modes were transverse and longitudinal. The amplifications in torsion were large compared to other parameters for curved and skewed bridges compared to straight bridge.