An Integrated Frp Strengthening and Damping System for Multiple Performance Level Seismic Retrofit of Rc Columns

The concept of an integrated strengthening and damping retrofit system was proposed to design reinforced concrete (RC) columns for their optimal performance under multi-level earthquake hazards. As illustrated in Figure 1, the system consisted of fiber reinforced polymer (FRP) sheets wrapping around a column and viscoelastic (VE) layers on the FRP sheets. The motion of the outer surface of the VE layers was constrained to the footing by applying another FRP sheet outside the VE layers and properly anchoring it into the footing. As such, two critical issues that will affect the performance of the proposed system are bonding between FRP sheets and VE layers, and anchorage of the outer FRP sheets into concrete. Both bond and anchorage mechanisms were investigated with laboratory tests. The FRP-VE interface failed in tearing of the VE materials and the FRP anchorage failed in concrete rupture. Design equation for anchorage has been developed as a result of this study.