Simple model for predicting torsional strength of reinforced and prestressed concrete sections

A noniterative method for calculating the ultimate torsional strength and the corresponding deformations of reinforced and concentrically prestressed concrete sections is presented. This method is based on the truss model. It avoids the need for iterations by making simplifying assumptions about the thickness of the concrete diagonal, the softening of the concrete due to diagonal cracking, and the principal compressive strain at ultimate conditions. A simple check on the spalling of the concrete cover is implemented. The calculated torsional capacities of 86 beams are compared with the experimental results and very good agreement is obtained.