Seismic Design Decision Analysis

Seismic design decision analysis is a procedure for organizing into a useful format the information required to arrive at a balance between the cost of designing to give earthquake resistance and the risk of damage and loss of lives in future earthquakes. The likelihood of ground shaking of various intensities is evaluated using Cornell's seismic risk model. Building performance is expressed by damage probability matrices; empirical evidence from past earthquakes — especially the San Fernando, Calif., earthquake — plus theoretical analysis and subjective judgment are used to develop such matrices. The cost of increased seismic resistance is determined by designing a series of typical buildings. All this information is then combined to provide estimates of costs and losses. The apparent conclusion is that design against earthquakes is justified only if one either makes a very consecutive interpretation of the seismic risk or places a very high value on saving lives.