A number of school gymnasia in Japan exhibited or lead one to foresee insufficient seismic performance, and seismic retrofits on them are still underway throughout the country. However, current assessment practices often require the replacement or addition of roof braces, which are very time and cost consuming. Energy dissipating retrofits are better suited than common strength-based retrofits to help reduce excited vibration of the roof and burden of the roof braces and ceilings, however, optimum design and evaluation methods remain unclear. This paper investigates retrofit design using elasto-plastic or viscous dampers, discussing its effects on response reduction for roof braces and practical response estimation methods, followed by proposing the retrofit method which achieves required seismic performances without replacing the roof braces.
