Punching Shear Enhancement of Flat Slabs with Partial Use of Ultrahigh-Performance Concrete
Publication: Journal of Materials in Civil Engineering
Volume 27, Issue 9
Abstract
Previous studies have clearly shown that flat slabs made of ultrahigh-performance concrete (UHPC) have considerably higher punching shear strength than their counterparts made of conventional concrete. However, it may not be economically feasible to construct an entire slab out of UHPC. As such, the objective of the research reported in this paper was to determine the optimal use of UHPC within the critical punching shear area, while the remainder of the slab is made of normal concrete. Ten flat slab specimens with two different steel reinforcement ratios and three different areas (or depths) of UHPC were tested under a concentric load to study the effect of UHPC on punching shear capacity of flat slabs. Test results showed that full-depth application of UHPC within the area enclosed by a perimeter located at a distance equal to the slab thickness from the column face could enhance punching shear capacity of the slab by 70%. This configuration was deemed to be the optimal application of UHPC in flat slabs. On the other hand, half-depth application of UHPC does not significantly improve shear capacity of flat slabs. The research reported in this paper also questioned the applicability of two available punching shear models for flat slabs made fully or partially out of reinforced UHPC.
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Acknowledgments
The writers are grateful to Lafarge North America, for providing the Ductal (UHPC) materials for the slab specimens. All experiments were carried out at the Titan America Structures and Construction Testing Laboratory of the Florida International University. Findings and opinions expressed in this paper, however, are those of the writers alone, and not necessarily the views of sponsoring agencies.
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Published In
Journal of Materials in Civil Engineering
Volume 27 • Issue 9 • September 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Jul 27, 2014
Accepted: Oct 14, 2014
Published online: Dec 5, 2014
Discussion open until: May 5, 2015
Published in print: Sep 1, 2015
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