Spacing of Reinforcement in Beams

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Title: Spacing of Reinforcement in Beams

Author(s): S. J. Chamberlin

Publication: Journal Proceedings

Volume: 53

Issue: 7

Appears on pages(s): 113-134

Keywords: no keywords

Date: 7/1/1956

Abstract:
The effect of spacing of parallel bars was studied in modified beams. Simulated variations in spacing were obtained by varying the width, of the concrete at the steel in different specimens. Two-point symmetrical loading was used on one- and two-bar specimens made with two different concretes. Steel consisted of # 4 bar-plain, old-style deformed, and modern deformed, and one modern # 6 bar. Embedded length-diameter ratios varied from 6 to 21.33. Bar slippages at the load points and at the free ends, deflections, and steel strains were measured. Ultimate loads increased with wider spacing until tensile failures developed. Measured bar slippages were greater for the narrowest spacing than for the others. All plain-bar beams failed by excessive slippage of the steel. Deformed-bar beams which did not fail in tension failed either by rupture of the concrete along a horizontal plane at the centerline of the steel or in combination with diagonal tension. Results indicate that an effective clear spacing of three bar diameters may be required.