Statistical Study on Moment-Rotation Curves of FRP Confined RC Columns

Document Type : Research Paper


1 Department of civil and environmental engineering, Shiraz University of Technology

2 Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran

3 Faculty of Civil and Environmental Engineering Department - Shiraz University of Technology


Columns are one of the main gravity and seismic load resisting elements in reinforced concrete (RC) buildings. Therefore, seismic retrofitting of these elements in vulnerable buildings is of great importance. For this purpose, various retrofitting techniques such as steel or RC jacketing and Fiber Reinforced (FRP) Laminates are proposed. Recently, using FRP laminates for confining the column or as the longitudinal reinforcement is considered by researchers. Although some guides and documents have been released for design of FRP strengthened RC elements, but for seismic evaluation of buildings by means of nonlinear analysis procedures the moment-rotation curve of the flexural elements as plastic hinges are required. But seismic rehabilitation instructions have only recommended the standard plastic hinges for non-retrofitted elements. Since the plastic hinge for different members should be derived from cyclic tests or reliable analytical procedures, in this article the cyclic test results which were performed on FRP confined RC columns are gathered and a statistical analysis is conducted on the key points of the curves. In this way, in addition to the evaluation of the affective parameters on the moment-rotation curves of FRP confined RC columns, a simple model is developed for plastic hinge of these elements in absence of a standard curve.