Title:
Lessons from Structural Performance – Slabs Containing Improperly Placed Reinforcing
Author(s):
Y. M. Lee, D. Mitchell, and P. J. Harris
Publication:
Concrete International
Volume:
1
Issue:
6
Appears on pages(s):
45-53
Keywords:
building codes, concrete construction; concrete slabs; cover; cracking (fracturing); crack width and spacing; deflection; epoxy resins; errors; flat concrete slabs; flexural tests; loads (forces); punching shear; reinforced concrete; reinforcing steels
DOI:
Date:
6/1/1979
Abstract:
This paper discusses the structural performance of slabs containing misplaced top reinforcing steel, before and after repair. The cracking behavior, the vertical position of top reinforcement, and the method of repair for an actual flat slab structure are described. In order to investigate the structural performance of such slabs, a series of flexural tests and punching shear tests were performed. The effects on the cracking behavior of vertically misplaced steel, load-deflection response, and ultimate capacity are discussed. Comparisons are made with two methods of repair; one with a reinforced concrete topping, and the other with extra reinforcement placed in grooves cut in the top surface of the slab followed by application of an epoxy-sand mortar. It is concluded that an increase in concrete cover with a corresponding decrease in effective depth results in more widely spaced cracks with larger crack widths, lower flexural stiffness, and reduced flexural and punching shear capacities. Both methods of repair significantly improved the overall structural performance.