ABSTRACT
In structural response analysis, SOLID65, 8-node solid elements with three degress of freedom per node are employed to simulate the concrete. Using such elements satisfies plastic derformation, cracking in three orthogonal directions, and crusing due to their quadratic interpolation functions. The steel reinforcement elements embedded in the concrete are represented by three-node truss elements LINK8. SHELL41 elements are used to model the FRP sheets. In the FE model, a ‘real strength model’ is established to consider the both factors, the FRP strength reduction and bond property deterioration, due to no work has been conducted on the accurate bond stress-slip behavior that
External bonding of fiber-reinforced polymer (FRP) plates or sheets (hereafter referred to as sheets only for brevity) has emerged as a popular technique for the strengthening of reinforced concrete (RC) members. However, very little information is available on the fire performance of FRP-strengthened RC members, and this is one of the primary impediments to using FRP in buildings. In this paper, three-dimensional finite element models are developed with ANSYS version 8.0 to predict the behavior of FRP-strengthened RC beams exposed to fire. The FE model consists of two calculation portions: temperature distribution analysis and structural response analysis. First, a nonlinear thermal analysis is carried out to determine the temperature distribution history within the element forming the beam under study. Second, the versions in the stiffness matrix due to changes in the materials properties of the structure are calculated accordingly, and a static analysis is performed in a number of time-steps until failure. The results from FE models are compared with the fire tests in terms of temperature-time and deformation-time curves of insulated strengthened beams and the model’s predictions are shown to agree with the test data satisfactorily.
