Behavior of RC Beams Strengthened with CFRP Laminates Under Fire - A Finite Element Simulation

Abstract

For the last two decades, the use of Fibre Reinforced Polymers (FRP) material has been successfully employed in many civil engineering applications. FRP strengthening systems are mainly used to retrofit existing and deficient structural members. There has been a lot of research on the performance of such strengthened structures at ambient temperatures. However, there is a lack of information on the behavior of RC beams externally strengthened with FRP systems when bonded to structural members when exposed to environmental hazards i.e. fire. In fact, many design codes are seeking further knowledge and data on the behavior of FRP strengthening systems under elevated temperatures, methods of fireproofing, and fire rating of concrete members strengthened with FRP systems [1]. For such reasons, code provisions associated with the use of FRP strengthening systems are quite conservative. Based on the recommendations of ACI 440.2-08: "Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures," [1] this thesis aims at investigating some of the areas that warrant further research and development of FRP strengthening systems under fire circumstances. Included is a detailed literature review that provides background information and the most important studies in this field. Finite element (FE) models developed and validated against experimental results published in the literature by other researchers. Overall, the developed FE models achieved good correlation with the experimental measured data. The validated FE model was then extended into parametric study to predict the behavior and response of the FRP system when subjected to fire. The parametric study includes different fire curves, different fire scenarios, different sustained live load levels and insulation schemes, types and thickness on the performance of the strengthened RC beams. Hence, the developed FE model could be used as a valid and economical tool to investigate the performance of strengthened RC beams with FRP systems under elevated temperature as an alternative to expensive and time consuming experimental investigations.