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Title: Flexure-Induced Punching: Calibration of Design Procedures

Author(s): Ramez B. Gayed and Chandana Peiris

Publication: Symposium Paper

Volume: 353


Appears on pages(s): 97-120

Keywords: concrete slabs; critical section; design; flat plate; flexure; punching shear; reinforcement ratio; yield-line.

DOI: 10.14359/51737114

Date: 7/1/2022

Wide flexural cracks, caused by yielding of flexural reinforcement above the columns, can extend deep through the slab thickness, join shear cracks and trigger punching shear failure. This is referred to as flexure-induced punching shear failure. It occurs by the development of a local mechanism of yield-lines above columns. Yield-line theory gives the minimum amount and extension of a zone of flexural reinforcement necessary to avoid the flexure-induced shear failure. ACI 318-19 requires a minimum amount of flexural reinforcement to be placed within an empirical width. Design equations are calibrated using published test data for slabs with or without shear reinforcement. Based on the used test data, a simplified equation is proposed for calculating the minimum flexural reinforcement to avoid the flexure-induced punching failure mode.