Strengthening of Laterally Restrained Steel Beams Subjected to Flexural Loading Using Low-Modulus CFRP

Abstract

Upgrading the flexural design strength of the structural member for increased live load without disrupting the functionality of the structure is an arduous task. One such problem was investigated in this study by using low-modulus (<125 GPa) carbon fiber–reinforced polymer (CFRP) for retrofitting of structural steel members. Although most researchers use normal (up to 250 GPa) or high-modulus (above 250–640 GPa) CFRP for flexural strengthening of steel structures, the use of low-modulus CFRP for such applications has been largely unexplored. The present study demonstrated the feasibility of low-modulus CFRP by experimental testing using different retrofitting techniques such as flange wrap, flange-web wrap, and closed wrap. A total of 18 steel beams were tested under four-point bending that includes two control specimens and 16 CFRP-strengthened specimens. In each strengthening scheme, enhanced CFRP wrapping configurations were introduced based on the failure modes observed from the previous wrapping configurations, thereby the strength, as well as the failure mode, improved. In general, the experimental results indicate that the design strength of the structural steel member subjected to flexural loading can be increased up to ∼50% by using the low-modulus CFRP strengthening schemes.