One-Way Shear in Wide Concrete Beams with Narrow Supports

Abstract

Wide reinforced concrete beams are frequently used as primary structural members in buildings or bridges, to support floor loads and to transfer forces from discontinuous walls or columns above. In these roles, these critical members may in turn be supported on walls extending across the full width of the beam, or on narrower columns. While punching shear capacity on a perimeter around the column must be checked in the latter case, design code provisions require that one-way shear capacity be assessed for a cross-section encompassing the full width of the beam for both the wall and column support configurations. There was concern that this full-width shear area approach may lead to poor predictions of one-way shear strength, due to local geometry influences at the wide-beam-to-narrow-column connection. An experimental program on 8 large-scale shear-critical reinforced concrete beams is presented, where the support or load width, relative to the member width, was a primary test variable. The results show that the one-way shear strength was moderately reduced as the support width to beam width ratio decreased. This influence occurred for members without shear reinforcement and for members with a moderate shear reinforcement ratio. A capacity reduction function was developed to account for this influence on one-way shear strength, and its application demonstrated with a design example.

Authors

Adam S. Lubell

University of Alberta, 3-028 NREF, Edmonton, Canada. E-mail: alubell@ualberta.ca

Evan C. Bentz

University of Toronto, 35 St. George St., Toronto, Canada. E-mail: bentz@ecf.utoronto.ca

Michael P. Collins

University of Toronto, 35 St. George St., Toronto, Canada. E-mail: mpc@ecf.utoronto.ca

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One-Way Shear in Wide Concrete Beams with Narrow Supports

One-Way Shear in Wide Concrete Beams with Narrow Supports

Authors