Strengthening by Stiffening: Fiber-Reinforced Plastic Configuration Effects on Behavior of Shear-Deficient Steel Beams
Publication: Journal of Composites for Construction
Volume 21, Issue 4
Abstract
Restoring the capacity of deficient structural members to meet original design requirements or new higher demands is common. For that purpose, research efforts to use composite materials in retrofitting steel structures have been gradually gaining ground in recent years, with more focus on inhibiting buckling modes by increasing local and/or global member stiffness. In this paper, the authors experimentally investigate retrofitting alternatives for shear-deficient steel structures. The proposed alternatives fall on what is referred to as strengthening by stiffening (SBS), in which thin-walled steel beams are retrofitted by bonding pultruded glass fiber reinforced polymer (GFRP) sections to the buckling-prone web panels. Different GFRP stiffener orientations, types, and adhesives were investigated in addition to conventional welded steel stiffeners, and bonded biaxial carbon fiber reinforced polymer (CFRP) sheets were tested in this study. The experimental results showed that gains in shear strength of up to 81% compared to non-retrofitted beams were achieved with bonded CFRP sheets, whereas an increase of about 50% in load capacity was achieved for bonded GFRP and welded steel stiffeners. The energy ductility of the retrofitted beams was found to be higher when a ductile epoxy type was used. Recommendations regarding the number of GFRP stiffeners, their orientation, type, and adhesive properties were drawn based on the findings from this paper. The results also showed that it may be possible to use SBS in new construction to eliminate conventionally welded steel stiffeners, which is known to introduce stress concentrations and their associated fatigue problems.
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Acknowledgments
This research is sponsored in part by the National Science Foundation, U.S. (CMMI# 1030575). The donation of materials by Fyfe Co., LLC, and Bedford Reinforced Plastics, Inc. in addition to support from Strongwell Corporation are greatly appreciated. Additional support from the Department of Civil and Environmental Engineering at Louisiana State University is also acknowledged.
Disclaimer
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsoring agencies.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 21 • Issue 4 • August 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Apr 18, 2016
Accepted: Oct 18, 2016
Published online: Feb 13, 2017
Discussion open until: Jul 13, 2017
Published in print: Aug 1, 2017
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