SHEAR-STRENGTH OF REINFORCED-CONCRETE DEEP BEAMS

Formulas to predict the ultimate shear strength of reinforced concrete deep beams are proposed. The derived equations are based on limit ana lysis theorems and associated flow rule. The lowest upper-bound soluti on is achieved through the work equation. With the effective strength concept, the materials are assumed to be perfectly rigid-plastic. A sp ecial constant is introduced to consider the structural effect on the effectiveness strength factor of concrete. For deep beams, this consta nt is equal to 1.25 - 0.25lambda, where lambda is the shear-span ratio of a deep beam. The interaction between horizontal and vertical web r einforcements is carefully analyzed. It is found that the yield condit ion of horizontal and vertical web reinforcements depends on the ratio of psi(h) and psi(v) or the degree of horizontal and vertical web rei nforcements. Comparisons with experimental work arc performed, and the y show good agreement between the proposed equations and test results.