Effectiveness of advanced composites in repairing heat-damaged RC columns
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ORIGINAL ARTICLE
Effectiveness of advanced composites in repairing heat-damaged RC columns Hanan Al-Nimry • Rami Haddad • Saad Afram Mohammed Abdel-Halim
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Received: 8 September 2012 / Accepted: 25 January 2013 RILEM 2013
Abstract Thirteen rectangular RC column specimens, constructed at 1/3 scale, were tested under axial loading to investigate the use of advanced composites in repairing heat-induced damage. Eleven of the column specimens were subjected to elevated temperatures of 500 C for 3 h. Nine heat-damaged columns were repaired using carbon fiber reinforced polymer (CFRP) sheets and plates. The effects of wrapping configuration, thickness of wrapping sheets, inclusion of plates as externally-bonded longitudinal reinforcement and the area of plates were examined using seven repair schemes. Test results confirmed that elevated temperatures adversely affect the axial load resistance and axial stiffness of the columns while increasing their toughness. Buckling under pure compressive loads was evident in heat-damaged columns except in those repaired using longitudinal CFRP plates. Partial wrapping with unidirectional CFRP sheets was found ineffective in augmenting the axial load capacity and stiffness of the damaged columns whereas full wrapping increased their axial load resistance and toughness. Using externally-bonded longitudinal CFRP plates, confined with circumferential wraps, significantly enhanced the initial axial stiffness and axial
H. Al-Nimry (&) R. Haddad S. Afram M. Abdel-Halim Department of Civil Engineering, Jordan University of Science and Technology, PO Box 3030, Irbid 22110, Jordan e-mail: [email protected]
load resistance of the damaged columns. However, none of the seven repair schemes investigated in this study managed to regain the original axial stiffness and load resistance of the undamaged columns. Keywords RC columns Heat-damaged columns Repair Advanced composites Carbon fiber reinforced polymer Axial loading
1 Introduction In skeleton concrete structures, columns play a key role in transferring dead and live loads from the superstructure to the foundations. For high rise buildings or in regions of high seismicity, columns are especially designed to resist additional lateral forces [1]. Hence, a higher safety margin is used for column design, as compared to other structural elements, to minimize the possibility of failure whether that is being through crushing of concrete, lateral buckling or both. Within their service lives, reinforced concrete structures may experience deterioration as a result of chemical, physical, electrochemical attacks, accidental fire or combinations thereof [2]. With the vast developments in quality control measures, codes and means for designing reinforced concrete structures as well as the enforcement of design and construction regulatory requirements by
Materials and Structures
national and local engineering agencies, the probability of structural failure of columns, as caused by unexpected additional loading or durability attac
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