Strengthening Long Steel Columns of S-Sections against Global Buckling around Weak Axis Using CFRP Plates of Various Moduli
Publication: Journal of Composites for Construction
Volume 19, Issue 4
Abstract
The traditional Euler’s buckling theory of slender columns indicates that column capacity depends on flexural rigidity (EI), rather than material strength. As such, the availability of ultrahigh modulus carbon fiber-reinforced polymer (CFRP) plates, which could be much stiffer than steel, can offer a unique alternative for strengthening slender steel columns, in lieu of welding or bolting steel plates. In this study, twelve 2.6 m long steel columns of 197 slenderness ratio that represents the upper limit permitted by code were tested under concentric axial loading using pin-ended conditions. The columns were allowed to buckle around their weak axes. CFRP plates were adhesively bonded to the flanges of the steel I-shape sections in nine of the columns. The main parameters studied were the level of initial out-of-straightness [ to ], CFRP modulus (168–430 GPa), CFRP reinforcement ratio (13–34%) and the length of CFRP plate (33–95% of L). The gain in axial strength due to CFRP retrofitting ranged from 11 to 29%, depending on the various parameters. The gain generally increased as CFRP modulus, initial out-of-straightness, or CFRP reinforcement ratio increased. Global buckling consistently governed the maximum load. In the case of the 430 GPa CFRP, buckling was followed by CFRP crushing in compression, then rupture in tension.
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© 2014 American Society of Civil Engineers.
History
Received: Jun 9, 2014
Accepted: Sep 15, 2014
Published online: Nov 3, 2014
Discussion open until: Apr 3, 2015
Published in print: Aug 1, 2015
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