Roof isolation with tuned mass based systems and application to a prefabricated building

The earthquake resistant design of prefabricated buildings is currently the focus of attention, especially for industrial buildings that require a high level of seismic protection. The standard design approach, based on ductility requirements, may succeed in preventing building collapse during a severe earthquake, but at the expense of accepting a high damage level at the column bases. To improve the seismic performance of such buildings, different innovative techniques have been proposed. However, these have not been widely implemented in engineering practice due, among others, to the lack of simple conceptual design methodologies. To achieve this goal, a methodology for the design of a roof isolation system is presented, where the roof isolation serves as non-conventional Tuned Mass Damper (TMD), giving a significantly reduced response in terms of displacements and forces. To that effect, design expressions for the TMD period and damping, depending on the building and soil characteristics, are proposed: the expressions have been calibrated based on numerical parametric time history analyses considering Eurocode 8 spectrum - compatible accelerograms. The application of the proposed methodology is demonstrated for a two-story prefabricated building.