Efficient Analysis of Beam Sections Using Softened Truss Model

In this paper, an efficient solution procedure is proposed to compute the pre-peak behavior of reinforced concrete (RC) beam cross sections under torsion and shear. This calculation procedure is based on the combined-action softened truss model (CA-STM), which idealizes rectangular RC cross sections as the association of four cracked panels. The proposed solution procedure formulates the problem as a system of nonlinear equations with constraints to be solved using optimization algorithms. The previsions obtained from this technique are compared with some experimental results of RC cross sections under pure torsion and torsion combined with shear, where good agreement was observed. Moreover, this procedure showed good computational efficiency, depicted by its ability to compute the load-deformation curves in few seconds. An analysis of a statically indeterminate structure incorporating beams under torsion and shear is also presented, for which a considerable decrease of the beam's torsional stiffness is observed under the combined actions.