Punching Failure and Compressive Membrane Action in Reinforced Concrete Slabs

Abstract

This study of punching failure and compressive membrane action in reinforced concrete slabs provides a basis for the development of a more realistic design approach for continuous slabs subjected to concentrated loadings.The results of an extensive series of tests on one quarter scale models of the interior slab—column connection in a flat slab structure are reported.From an examination of the experimental evidence, fundamental concepts of slab behaviour are established and a rational method for the prediction of the punching strength of the conventional slab specimen is developed. This delineates between the various modes of punching failure, which are broadly classified as either flexural or shear. The criterion for the ultimate flexural capacity is based on elastic—plastic theory and consists of aninterpolative factor which relates the applied load to the slab moment of resistance. The ultimate shear capacity is governed by the load to cause internal diagonal cracking of the slab, prior to yielding of the reinforce mentor crushing of the concrete.In order to include the effect of compressive membrane action in the method of analysis, a theory for arching action in slab strips is derived.This is combined with the rational method for the conventional slab specimen to produce the integrated procedure for the prediction of the enhanced punching strength of laterally restrained slabs. The procedure is presented as a rigorous method which is suitable for the analysis of slabs for which the degree of lateral restraint can be accurately assessed. Furthermore, a simplified approach which is applicable to the interior slab-column connection in a flat slab structure is proposed. The assumptions upon which the procedure is based are validated by the good correlation obtained from acomparison of the predicted failure loads with a wide range of test resultsfrom various sources.

Date of Award	1982
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	A. E. Long (Supervisor)