Fire Behavior of Thin CFRP Pretensioned High-Strength Concrete Slabs
Publication: Journal of Composites for Construction
Volume 16, Issue 4
Abstract
More sustainable precast concrete structural elements are emerging from the research community utilizing high-strength, self-consolidating fiber-reinforced concrete (HPSCC) reinforced with noncorroding prestressed carbon-fiber-reinforced polymer (CFRP). An example of this is a new type of precast CFRP pretensioned HPSCC panel intended as load-bearing beams or columns for use in building envelopes. Such elements have recently been applied to architectural façade elements in Europe. A key issue in the implementation of these elements as load-carrying members in buildings is demonstrating satisfactory performance in fire. It is well known that the bond between FRP reinforcing bars and concrete deteriorates at elevated temperatures. It is also known that high-strength concrete is susceptible to explosive spalling when subjected to fire. Reductions in FRP reinforcement tensile and bond strength during fire, effects on the load-bearing capacity of prestressed concrete structures, and the explosive spalling response of HPSCC during fire all remain largely unknown. This paper provides insights into the fire behavior of CFRP prestressed HPSCC slabs through an experimental study on thin slabs exposed to a standard fire while subjected to sustained service loads. It is shown that the fire resistance of these elements is governed by fire-induced spalling or, if spalling is prevented by the use of high dosages of polypropylene microfibers in the concrete, by thermal splitting-crack-induced bond failure of the CFRP tendons in their prestress transfer zone. Neither reductions in tensile strength of the tendons nor reductions in bond strength due to resin softening at high temperature appeared to play critical roles for the tests described in this paper. Key areas for future research are highlighted.
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Acknowledgments
The authors would like to thank SACAC Schleuderbetonwerk AG and in particular their managing director, Mr. Georges Bättig, and its R&D engineers, Mr. Jacek Gwozdz and Birol Kanik. Alex Stutz, Daniel Völki, Manfred Heiniger, Walter Bollier, Angelo Demont, and Marcel Steiner are also acknowledged. Special thanks are due to Dr. Pietro Lura for concrete moisture and RH measurements and to Mr. Cristián Maluk, Ph.D. candidate at the University of Edinburgh, for many helpful remarks on the manuscript. This research was partially funded by the Commission for Technology and Innovation (CTI) of the Swiss Confederation.
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Information
Published In
Journal of Composites for Construction
Volume 16 • Issue 4 • August 2012
Pages: 381 - 394
Copyright
© 2012. American Society of Civil Engineers.
History
Received: Jul 13, 2011
Accepted: Dec 8, 2011
Published online: Dec 10, 2011
Published in print: Aug 1, 2012
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