Experimental Study on Cracking and Ultimate Behavior of Prestressed Concrete Slabs

Abstract

The object of this study was to examine the mechanical behaviors of prestressed concrete slabs from their cracking to final stage. The effects of the loading position, the level of prestressing and the width/span ratio of slab specimens were investigated on the cracking and failure load, failure pattern and deflections. The specimens were simply supported along two opposite edges. A uniformly distributed load having an 8×8cm loading area was applied on the center of a specimen (Case C) or on a position apart from the center (Case E).
Flexural failure occured in the Case C, while both flexural and punching shear failures were observed in the Case E. Punching failure occured especially in the wide specimens subjected to small longitudinal but no transverse prestressing. Prestressing in the transverse direction was found to improve the flexural rigidity and to change the cracking and failure pattern from a shear to a flexure type. However, the prestressing did not seem to affect the cracking load of specimens. After cracking, the central deflection of the specimens with transverse prestressing was much larger than that of those specimens without prestressing. The ultimate strength in flexure could be conservatively estimated by “Yield-Line Theory”, while that in punching shear could be safely predicted by Hawkins' equation.