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Title: Punching shear in normal and lightweight aggregate reinforced concrete slabs.
Author: Wady, D. A.
Awarding Body: University of Wales Institute of Science and Technology
Current Institution: Cardiff University
Date of Award: 1977
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The results of an experimental and theoretical investigation into the behaviour of reinforced concrete flat slab-column connections are presented. In the experimental programme 33 lightweight and 8 normal weight slabs were failed in punching shear. The specimens were simply supported and loaded vertically through central, monolithic column stubs. Three lightweight aggregates were used, and the concrete strength and section depth varied. It was found that slabs made with Lytag, Solite and limestone aggregates failed at similar loads, but slabs made with Leca aggregate concrete failed at approximately 70% of the former group (other variables being equal). In the theoretical investigation an analysis was developed to model the various stages of the slabs' behaviour under increasing load. The analysis enabled the critical pre-failure and punching loads to be calculated. Satisfactory agreement was established between the pre-failure values. The load at which failure occurred in the compression zone was computed using one of two methods designed to accommodate the differing characteristics of the concretes used. The methods depend on an idealisation of the behaviour of the shear crack which enables the compression zone stresses to be. established. Comparison of these stresses with a criterion of failure gives the concrete failure load. The ultimate punching load includes the enhancing effects, on the concrete failure load, of inplane stresses and dowel action. Good agreement between the theoretical, and. experimental punching values was established. The thesis includes a review of previous experimental and analytical work performed on normal and lightweight aggregate slabs. The existing empirical data is shown to be limited in several areas, especially for lightweight aggregate concrete tests. The application of existing formulae to the present experimental work does not provide a satisfactory agreement with the results. Three of the equations axe re-evaluated to pr6vide a closer fit with the present test results and for a wider based group of lightweight aggregate tests. The provisions of ACI 318-71 and CP. 110 : 1972 are also applied to the slabs of the present test series, and are shown to be conservative. Finally recommendations for future work are given.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Shear stresses in concrete