Cost-performance criteria for seismic retrofitting

A methodology to facilitate the decision making process for seismic retrofitting of buildings is presented. To this end, the damage cost to a building is calculated as the sum of direct flows from the capital stock and human capital. Four damage cost functions are considered. These are the replacement or repair cost, loss of contents, human injury and fatality, and economic loss. The damage cost functions are conveniently expressed in terms of a global damage index, D$\rm\sb{m},$ which is a qualitative measure of the building performance after an earthquake. The Park-Ang damage model was incorporated into the SNAP-2D computer program in order to calculate damage indices for reinforced concrete members. Using the weighting scheme proposed by Bracci, the global damage index for the building structure is evaluated. Henceforth, the cost-performance methodology is implemented for reinforced concrete building prototypes in Puerto Rico. Two classes of building prototypes are considered. Class 1 buildings are older buildings that were properly designed for the time of their construction but may not be adequate by the current standards. Class 2 buildings are buildings that are designed using the current building code regulations. In all cases, steel bracing systems are the retrofitting schemes of choice. Results from an Input-Output analysis are used to estimate the economic losses for different classes of occupancies. Other factors explicitly considered are the socio-economic status of building population, business density, reconstruction time, and earthquake recurrence rates. The methodology also allows the designer to generate different cost schedules for different clients simultaneously. As the needs of potential clients may vary considerably, the process will address any specific concerns, whether the client is the owner, the business occupant, the government, or the insurance company.