Lapped Splices in Reinforced Concrete Beams


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Title: Lapped Splices in Reinforced Concrete Beams

Author(s): James Chinn, Phil M. Ferguson, and J. Neils Thompson

Publication: Journal Proceedings

Volume: 52

Issue: 10

Appears on pages(s): 201-213

Keywords: no keywords

Date: 10/1/1955

Tests on spliced reinforcement were performed under condit ions where longitudinal splitting was not prevented to study the effect of such splitting on bond capacity. Splices were selected as representative of tension lap splices that might occur in joining precast beams in negative moment regions. Failures were mostly of two kinds, horizontal splitting extending through the beams at the level of the bars and vertical longitudinal cracks through the bottom cover over the bars. Study included effect of the following: beam width, cover over steel, length of splice, space between splice bars, bar size, stirrups in splice zone, number of splices in a beam, splice position (top or bottom), and various cylinder strengths. It. was found that: increased beam width increased splice strength; increased cover increased splice strength in shorter splices; unit bond stress decreased with increasing splice length, but not as rapidly as surface area increased. splice position had little effect on strength; bar size had an effect on bond strength even when cover, splice length, and beam width were constant in tcsrms of bar diameters; stirrups increased splice strength; little difference in strength occurred between contact and spaced splices; and if bond stress is not limited to IT5 psi (as against allowable 350 psi) for SC = 4500 psi and #6 bottom bars, a safety factor of 2.5 will not always be obtained.