Seismic Response of FRP-Upgraded Exterior RC Beam-Column Joints
Publication: Journal of Composites for Construction
Volume 14, Issue 2
Abstract
Shear failure of exterior beam-column joints is identified as the principal cause of collapse of many moment-resisting frame buildings during recent earthquakes. Effective and economical strengthening techniques to upgrade joint shear resistance and ductility in existing structures are needed. In this paper, efficiency and effectiveness of carbon fiber-reinforced polymer (CFRP) sheets in upgrading the shear strength and ductility of seismically deficient exterior beam-column joints have been studied. Four as-built joints were constructed with nonoptimal design parameters (inadequate joint shear strength with no transverse reinforcement) representing preseismic code design construction practice of joints and encompassing most of existing beam-column connections. Out of these four as-built specimens, two specimens were used as baseline specimens (control specimens) and other two were strengthened with CFRP sheets under two different schemes (strengthened specimens). In the first scheme, CFRP sheets were epoxy bonded to joint, beams, and part of the column regions. In the second scheme, however, sheets were epoxy bonded to joint region only but they were effectively prevented against any possible debonding through mechanical anchorages. All of these four subassemblages were subjected to cyclic lateral load histories so as to provide the equivalent of severe earthquake damage. The damaged control specimens were then repaired by filling their cracks through epoxy and externally bonding them with CFRP sheets under the same above two schemes. These repaired specimens were subjected to the similar cyclic lateral load history and their response histories were obtained. Response histories of control, repaired, and strengthened specimens were then compared. The results were compared through hysteretic loops, load-displacement envelopes, column profiles, joint shear distortion, ductility, and stiffness degradation. The comparison shows that CFRP sheets are very effective in improving shear resistance and deformation capacity of the exterior beam-column joints and delaying their stiffness degradation.
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Acknowledgments
The experimental work conducted by the writers and described in this paper was performed at the Structural Engineering Lab of the Civil Engineering Department—King Saud University and was jointly funded by King Abdulaziz City for Science and Technology (KACST) and the SBG Chair of Research and Studies in Strengthening and Rehabilitation of Structures.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 14 • Issue 2 • April 2010
Pages: 195 - 208
Copyright
© 2010 ASCE.
History
Received: Jan 13, 2009
Accepted: Aug 27, 2009
Published online: Mar 15, 2010
Published in print: Apr 2010
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