Title:
Flexure-Shear Interaction Model for Longitudinally Reinforced Beams
Author(s):
Gaetano Russo, Gaetano Zingone, andGiovanni Puleri
Publication:
Structural Journal
Volume:
88
Issue:
1
Appears on pages(s):
60-68
Keywords:
beams (supports); diagonal tension; failure; flexural strength; mathematical models; moments; reinforced concrete; reinforcing steels; shear strength; span-depth ratio; structural analysis; Design.
DOI:
10.14359/3113
Date:
1/1/1991
Abstract:
An analytical model is proposed for predicting the relative flexural capacity Mu / Mfl, i.e., the ratio of the moment capacity with interaction to moment capacity in pure flexure. The study concerns longitudinally reinforced concrete beams or one-way slabs without shear reinforcement failing under the combined influence of flexure and shear. For these structural elements, it is possible to obtain the "valley of diagonal failure," i.e., the variation of u / Mfl with the shear pan-to-depth ratio a/d and reinforcement ratio {rho}. Moreover, an expression is determined giving the a/d ratio at which the minimum value of the flexure capacity under shear and moment interaction is attained. At the minimum flexural capacity, the moment contribution due to beam action is analytically found to be 60 percent of the total capacity. It is further shown that the expression for the a/d ratio corresponding to minimum flexural capacity also gives the critical a/d ratio distinguishing failure at diagonal cracking from failure by crushing or splitting of concrete. The {rho} versus a/d function is obtained at which no reduction of flexural capacity occurs (Mu / Mfl = 1). This function, together with the expression of the critical a/d ratio, makes it possible to predict whether flexural, shear compression, or diagonal tension failure will occur.