Seismic Behavior of Concrete Columns Reinforced by Steel-FRP Composite Bars
Publication: Journal of Composites for Construction
Volume 15, Issue 5
Abstract
Steel-fiber-reinforced polymer (FRP) composite bars (SFCBs) are a novel reinforcement for concrete structures. Because of the FRP’s linear elastic characteristic and high ultimate strength, they can achieve a stable postyield stiffness even after the inner steel bar has yielded, which subsequently enables a performance-based seismic design to easily be implemented. In this study, lateral cyclic loading tests of concrete columns reinforced either by SFCBs or by ordinary steel bars were conducted with axial compression ratios of 0.12. The main variable parameters were the FRP type (basalt or carbon FRP) and the steel/FRP ratio of the SFCBs. The test results showed the following: (1) compared with ordinary RC columns, SFCB-reinforced concrete columns had a stable postyield stiffness after the SFCB’s inner steel bar yielded; (2) because of the postyield stiffness of the SFCB, the SFCB-reinforced concrete columns exhibited less column-base curvature demand than ordinary RC columns for a given column cap lateral deformation. Thus, reduced unloading residual deformation (i.e., higher postearthquake reparability) of SFCB columns could be achieved; (3) the outer FRP type of SFCB had a direct influence on the performance of SFCB-reinforced concrete columns, and concrete columns reinforced with steel-basalt FRP (BFRP) composite bars exhibited better ductility (i.e., a longer effective length of postyield stiffness) and a smaller unloading residual deformation under the same unloading displacement when compared with steel-carbon FRP (CFRP) composite bar columns; (4) the degradation of the unloading stiffness by an ordinary RC column based on the Takeda (TK) model was only suitable at a certain lateral displacement. In evaluating the reparability of important structures at the small plastic deformation stage, the TK model estimated a much smaller residual displacement, which is unsafe for important structures.
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Acknowledgments
The authors would like to acknowledge financial support from the National Basic Research Program of China (973 Program) (No. UNSPECIFIED2007CB714200), the National Natural Science Foundation of China (No. NNSFC51078077), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the Natural Science Foundation of Jiangsu Province, China (No. UNSPECIFIEDBK2009288), and supplementary support from the Jiangsu Civil Engineering Graduate Center for Innovation and Academic Communication Foundation, China.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 15 • Issue 5 • October 2011
Pages: 696 - 706
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Sep 8, 2010
Accepted: Dec 15, 2010
Published online: Jan 12, 2011
Published in print: Oct 1, 2011
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