A simplified method to predict the fire resistance of RC beams strengthened with near-surface mounted CFRP

A simplified method was proposed to predict the fire resistance of flexure-dominated reinforced concrete (RC) beams strengthened with near-surface mounted (NSM) carbon fiber reinforced polymer (CFRP). Based on the results of previous experimental observations and theoretical analyses, “steel yielding after FRP slipping” and “FRP fracture after steel yielding” were presumed to be the possible failure modes for NSM-FRP strengthening system under fire. An algorithm was thus developed to evaluate the fire resistance of the strengthening system. A series of pull-out tests were carried out to obtain the bond-slip relationships of NSM-FRP at different elevated temperatures for the proposed algorithm. Then this method was used to predict the fire resistance of nine RC beams strengthened with NSM-FRP, which were subjected to a sustained load and the ISO834 standard fire. The predictions showed good agreement with the test results, indicating the effectiveness of the proposed method. This study provides a helpful reference for the fire resistance design of flexure-dominated RC beans strengthened with NSM-FRP in engineering practice.