Plastic Rotation of an RCC T-Beam Bridge Girder under the Combined Influence of Flexure and Torsion

Abstract

In the nonlinear analysis of a reinforced concrete T-beam bridge superstructure using grillage idealization, and rigid–plastic idealization of moment–curvature and torque–twist relationships of the resulting grillage members, it becomes necessary to compute the plastic rotation capacity of the resulting T-beam bridge girder due to limited ultimate strain capacity of concrete. An idea about the plastic rotation capacity of these members enables one to determine the true ultimate load carrying capacity of this type of structure, extent of redistribution of stresses at failure, and ductility of the structure. This paper presents analytical methods to determine the plastic rotation capacity of reinforced cement concrete T-beam bridge girder (or grillage member) under the combined influence of flexure and torsion. The methods have been validated by experiments. The analytical methods are based on skew-bending and space truss theories. The tests have been carried out on 1:6 microconcrete models. The salient conclusions have been enumerated.