Simple Method for Predicting Temperatures in Insulated, FRP-Strengthened RC Members Exposed to a Standard Fire

Fire safety is a significant concern for fiber-reinforced-polymer (FRP)-strengthened RC structures, particularly for indoor applications. To satisfy fire resistance requirements, fire insulation layers may be provided to protect FRP-strengthened RC members. This paper presents a simple, design-oriented method for predicting temperatures in insulated FRP-strengthened RC members under standard fire exposure. The proposed method consists of two sets of formulas: one set for predicting temperatures in unprotected FRP-strengthened RC members exposed to a standard fire; and another set to convert a fire insulation layer into an equivalent concrete layer. As a result, an insulated FRP-strengthened RC member can be analyzed as an unprotected RC member with an enlarged section for which a similar simple method has previously been established by these authors. In the present study, a finite element (FE) approach for the temperature analysis of insulated FRP-strengthened RC members was first developed and then verified using existing test data. Then the verified FE approach was employed in a parametric study to generate extensive numerical data, on which the second set of formulas were established. The proposed temperature prediction method is shown to provide accurate predictions of both FE results and test data of insulated FRP-strengthened RC members.