Effective Torsional Rigidity of Reinforced Concrete Members

摘要

This paper presents a simple procedure for calculating the effective torsional rigidity of reinforced concrete members. The torsional rigidity of a reinforced concrete member, such as a spandrel beam, determines the amount of rotation that the member undergoes, and that, in turn, determines the amount of end moment that will be transferred by the supported transverse member to the spandrel beam. Thus, the effective torsional rigidity is an important parameter for three-dimensional analysis of reinforced concrete structures. The method presented in this paper relates torsional rigidity to the applied torque, taking the effect of reinforcement into account. The method is applicable throughout the entire loading history from the uncracked state to the fully cracked state and even up to the ultimate limit state. Prior to cracking, the elastic and uncracked torsional rigidity of the section is used. After the formation of torsional cracking, the proposed procedure interpolates between torsional rigidities immediately after cracking and that at the ultimate limit state. The proposed procedure has been verified by comparing its predictions with test data available in the literature. Comparison between the computed and experimental torque-twist curves shows that the proposed procedure for computing effective torsional rigidity is reasonably accurate.