Shaking table testing of retrofitted 3-storey building

The paper investigates the seismic performance of an existing 3-storey structure, built in the 70's. Not complying with capacity design principles, the structure is prone to soft-storey collapse, calling for retrofit through addition of shear walls. Two alternatives are considered with respect to the foundation: (a) conventional design; and (b) rocking isolation. In the latter case, the foundation is intentionally "under-designed" to fully mobilize its capacity acting as a "fuse". A reduced-scale model of the soil-structure system is tested in the shaking table of the Laboratory of Soil Mechanics. At reduced-scale, it is practically impossible to maintain similarity in terms of stiffness, and achieve the desired bending moment capacity of structural members at the same time. Therefore, each beam-column connection is modeled with artificial plastic hinges. It is shown that the rocking-isolated structure outperforms the conventional design, when subjected to very strong seismic shaking.