Seismic retrofitting of reinforced concrete bridge frames using external bonded FRP sheets

Abstract

Following the strong earthquakes like Hyogoken Nanbu earthquake in 1995 and Niigataken Tyuetsu Earthquake in 2004, many RC viaducts in Japan were strengthened in the columns. The ductility of such structures, however, may still be limited due to the potential shear failure at the beams. In this research, experimental investigations were conducted in order to study the possible enhancement of seismic behavior of beams by externally bonded fiber reinforced polymer (FRP) sheets. In shear strengthening beams using FRP sheets, full wrapping is not always possible and in U-wrapping, debonding failure of FRP sheet limits the proper utilization of its strength. Therefore, in this research FRP sheets were mechanically anchored to the beams. A total number of six specimens with different wrap configurations and mechanical anchorage schemes were tested. Experimental results showed that a proper selection of mechanical anchorage scheme for FRP sheet in U-wrap portion is necessary for the significant enhancement of shear strength of RC beam close to that of a fully wrapped beam.