Performance based assessment of FRP-retrofitted existing RC frames

In recent years, performance based design has become universally acceptable in seismic assessment of structures. Using this design method, performance of existing and retrofitted RC buildings can be evaluated based on the criteria suggested by ATC-40 and FEMA-356 using nonlinear pushover analysis. In this paper, performance of an FRP-retrofitted RC frame is assessed and the result is compared with steel-braced frames and unstrengthened moment resisting frames. The strong-column weak-beam principal is employed in this study. Firstly, the flexural stiffness of FRP-retrofitted joints of an existing RC ordinary moment resisting frame is determined using nonlinear finite element analysis. It is then implemented into a mathematical model for the web-bonded FRP-retrofitted frame developed by the first two authors. Subsequently, the base frame and retrofitted frames (both steel-braced and FRP-retrofitted) are analysed using nonlinear pushover analysis method. Finally, the seismic performance of the FRP retrofitted frame is compared with the corresponding base frame and steel-braced frames reported by others. The results show that the improvement in ductility and performance level of the existing RC frames is better for frames retrofitted with FRPs than the steel-braced systems.