Title: Shear Capacity of Reinforced Lightweight High-Strength Concrete Beams

Author(s): Miguel A. Salandra and Shuaib H. Ahmad

Publication: Structural Journal

Volume: 86

Issue: 6

Appears on pages(s): 697-704

Keywords: beams (supports); high-strength concretes; lightweight concretes; reinforced concrete; shear strength; span-depth ratio;; web reinforcement; Structural Research

DOI: 10.14359/2741

Date: 11/1/1989

Abstract:
Sixteen beams made of lightweight high-strength concrete were tested to determine their diagonal cracking and ultimate shear capacities. The variables in the test program were concrete strength, which varied between 7800 and 10,500 psi (53.8 and 72.5 MPa); shear span-depth ratios a/b = 0.56, 1.56, 2.59, and 3.63; and web reinforcement. Eight of the test beams had no reinforcement and the other eight had web reinforcement along the entire length of the beam. Test results indicate that the ACI Building Code predictions of Eq. (11-3) and (11-6) for lightweight concretes are unconservative for beams with tensile steel ratios of 1.45 percent, a/b ratios greater than 3.63, and compressive strengths in excess of 10,000 psi (69 MPa). Through a more rational approach to compute the contribution of concrete to the shear capacity, a postcracking shear strength in concrete is observed.