Title: High-Strength Concrete Deep Beams With Effective Span and Shear Span Variations

Author(s): Kang-Hai Tan, Fung-Kew Kong, Susanto Teng, and LingweiI Guan

Publication: Structural Journal

Volume: 92

Issue: 4

Appears on pages(s): 395-405

Keywords: building codes; deep beams; deflection; diagonal tension; high-strength concrete; shear strength; spans; strength; tension; web reinforcement; Structural Research

DOI: 10.14359/991

Date: 7/1/1995

Abstract:
Nineteen reinforced concrete deep beams with compressive strengths in the range of 41 MPa less than or equal to 59 MPa (6000 psi less than or equal to 8600 psi) were tested under two-point top loading. All the beams were singly reinforced with main steel percentage of 1.23 percent and with nominal percentage of shear reinforcement of 0.48 percent. The beams were tested for seven shear span-depth ratios a/d, ranging from 0.27 to 2.70, and four effective span-depth ratios a/d ranging from 2.15 to 5.38. Test results indicate that l e/d has little influence on the magnitude of the failure load. But for beams with a/d greater than or equal to 1.00, the flexural failure mode becomes dominant with increasing l e/d. The test results are compared with predictions based on the current ACI Building Code. The comparisons reported in this paper will provide an added assurance to designers that the deep-beam provisions in the ACI code, though essentially based on concrete strength of less than 412 MPa (6000 psi), will insure safe designs for higher strength deep beams. However, the ACI code tends to be rather conservative, as shown by comparison to the Deep-Beam Design Guide issued by the Construction Industry Research and Information Association, London. Nevertheless, the ACI code has the important advantage of being easy to use.