Stress Field in Web of RC Thin‐Webbed Beams Failing in Shear

Abstract

The resistant mechanisms of reinforced and prestressed thin‐webbed beams failing in shear are effective on the condition that the web reinforcement and thickness are suitably designed. With regard to this, a rational model is developed for the limit analysis of a thin web at the onset of shear collapse because of stirrup yielding, also considering the aggregate interlock (along the shear cracks), the bending stiffness of the inclined concrete struts, the bond properties of the stirrups, and the ultimate capacity (in shear and compression) of the struts. The proposed model is an improved version of the well‐known Mörsch's truss, which is well suited to the modeling of a regularly cracked web subjected to prevailing shear. By solving a nonlinear system of equations regarding the equilibrium, compatibility, constitutive laws of the web, and various contributions to the web state of stress are investigated. The assumption introduced by other scholars, and adopted here also, that the web be subjected to a diagonal compression field, proves to be based on clear physical phenomena.