Experimental Seismic Structural Performance Evaluations of RC Columns Strengthened by Stiff-Type Polyurea

Recently, strong earthquakes are continuously occurring all over the world regarding, repair and strengthening of non-seismically designed structures. Presently, fiber-reinforced polymer (FRP) surface-bonding method is used as a quick and easy way to retrofit and strengthen damaged columns and walls. However, the inherent problems of the FRP surface-bonding method of bond degradation are adhesive interfaces and FRP sheet aging during service-life still. In order to overcome these problems, it is necessary to develop new materials and techniques that can induce monolithic behavior between the structural member and retrofit material by eliminating the bonding interface. One solution is to use repair and strengthening using stiff-type polyurea (STPU) developed as a seismic retrofitting material which can be applied by spraying method. In order to investigate the retrofitting effect of STPU, pseudo-dynamic push–pull test and dynamic shaking table tests are performed. The novelty of the study is that the RC columns strengthened with a newly developed STPU are tested for pseudo-dynamic (i.e., also represents the static behavior) and dynamic behavior. From the test results, overall strengthening effect of the STPU for both static and dynamic loading conditions can be understood, which can be used for retrofitting of concrete structures all over the world. The study results are discussed in detail in the paper.