A number of school gymnasia in Japan built in the 1970s in Japan have exhibited or lead one to foresee insufficient seismic performance, and seismic retrofits on them are still underway throughout the country. However, current assessment practices do not take into account the vertical vibration excitation peculiar to raised roofs, which heavily impacts the collapse of non-structural elements, such as ceiling components or lighting equipment. Energy dissipating retrofits are better suited than common strength-based retrofits to help reduce such excited vibration, however, optimum design and evaluation methods remain unclear. This paper looks at the typical school gymnasia in Japan, and investigates retrofit design using elasto-plastic or viscous dampers, discussing its effects on roof response reduction and practical response estimation methods.
