Title: Shear Strength of Restrained Concrete Beams Without Web Reinforcement

Author(s): John E. Bower and Ivan M. Viest

Publication: Journal Proceedings

Volume: 57

Issue: 7

Appears on pages(s): 73-98

Keywords: none

DOI: 10.14359/8012

Date: 7/1/1960

Abstract:
Tests of two series of reinforced concrete beams with- out web reinforcement were made to investigate the behavior in shear of restrained beams. One series was designed as a study of the effects of variations in the ratio of maximum negative moment to the maximum positive moment (moment ratio). The other series was concerned with the effects of variations in the ratio of maximum moment to shear (moment-shear ratio = M/F’& The tests have shown that the effect of shear on the behavior of restrained beams is essentially the same as that observed for simple beams: the shear affects the load-deformationcharacteristics and the strength of a beam through the formation of diagonal tension cracks. The first diagonal tension crack forms at a section subjected to both moment and shear and located between the point of contraflexure and the section of maximum moment. An analysis of the test data has shown that the initial diagonal tension cracking strength is a function of the moment-shear ratio rather than of the length of the shear span. Large variations were found in the strength beyond the initial diagonal tension cracking loads even for companion specimens. This finding supports earlier suggestions that the strength in excess of the diagonal tension cracking load is of little practical value. Equations are presented for the initial diagonal tension cracking strength and for the shear-moment capacity.