Seismic evaluation of FRP strengthened RC buildings subjected to near-fault ground motions having fling step

Recordings from recent earthquakes have provided evidence that ground motions in the near field of a rupturing fault differ from ordinary ground motions, as they can contain a large energy, or “directivity” pulse. This pulse can cause considerable damage during an earthquake, especially to structures with natural periods close to those of the pulse. Failures of modern engineered structures observed within the near-fault region in recent earthquakes have revealed the vulnerability of existing RC buildings against pulse-type ground motions. This may be due to the fact that these modern structures had been designed primarily using the design spectra of available standards, which have been developed using stochastic processes with relatively long duration that characterizes more distant ground motions. Many recently designed and constructed buildings may therefore require strengthening in order to perform well when subjected to near-fault ground motions. Fiber Reinforced Polymers are considered to be a viable alternative, due to their relatively easy and quick installation, low life cycle costs and zero maintenance requirements. This paper presents the results of a study of the response of typical existing RC buildings to near-fault ground motions and the potential improvements achievable after FRP retrofitting of the buildings. Results demonstrate the successful implementation of FRP with an improvement in stiffness, strength and lateral displacement capacity of the rehabilitated structure. It is demonstrated that strengthening with FRP is very effective in reducing drift demands for structures for a wide range of natural periods.