A simplified method to select effective seismic retrofit for steel buildings based on damage cost

Recent earthquakes have highlighted the vulnerability of nonstructural components. Nonstructural damage causes serious injuries and economic loss1) but current seismic design methodologies consider nonstructural damages indirectly by checking drift limits. Note that the drift capacity of nonstructural components varies depending on the type of component. In order to reduce loss by earthquakes, seismic retrofit is an effective option. Currently, retrofit systems are designed to increase a building’s capacity to avoid collapse, but retrofit can also be effective in reducing monetary loss due to non-structural damage if designed appropriately. In terms of monetary loss, seismic retrofit can be considered effective when reduction in repair costs (adjusted for inflation) becomes larger than the initial and maintenance costs. The process of estimating losses in future earthquakes fairly complicated because it requires a series of hazard, structural, damage and loss analyses. For retrofit projects, where cost and time in planning has severer limitations than for new building projects, it is impractical for structural engineers to conduct detailed loss estimation. Moreover, particularly in Japan, hazard analysis is commonly not considered well in practice. It is therefore difficult for structural engineers to practically undertake detailed loss estimation in addition to structural design. Considering this situation, this paper aims to develop a simplified method to roughly estimate monetary loss due to future earthquakes and to demonstrate the use of the proposed method for selecting cost-effective seismic retrofitting systems