Softened Truss Model Theory for Shear and Torsion

Abstract

The softened truss model theory, which has recently been developed for shear and torsion of reinforced concrete members, is summarized in a systematic and unified manner. Eleven equations involving fourteen variables are derived from equilibrium, compatibility, and materials conditions to solve the shear problem. An additional six equations involving six more variables are required to treat the torsion problem. The theory was successfully applied to structures where shear behavior predominates, such as low-rise shearwalls, framed wall panels, deep beams, and shear transfer strengths. It also worked very well for members subjected to torsion. Efficient algorithms are proposed to solve the simultaneous equations for different types of structures. The theoretical predictions are in good agreement with the test results in all cases. The prediction includes not only the shear and torsional strengths, but also the deformations of structures throughout their post-cracking loading history.