A conception of casualty control based seismic design for buildings

Earthquake disaster is still the number one among all natural disasters, particularly, in terms of destructive power in causing deaths. Can earthquake engineers control seismic casualties through the seismic design of buildings? For this purpose, a conception of casualty control based seismic design is presented and a “two-step decision-making” method is proposed for determining the optimum seismic design intensity (or ground-motion) for controlling both seismic death and economic losses. The key problems in establishing the model are to determine the appropriate socially acceptable level of earthquake mortality and establish the corresponding objective function and /or constraint conditions in determining the optimum seismic design intensity. Ten different grades of socially acceptable mortality are suggested and the final socially acceptable mortality level was proposed for seismic design based on a questionnaire that was distributed nationwide in China. Finally, the method was applied to eight cities with different seismic hazard in China and the effects of various grades of acceptable earthquake mortality on seismic design intensity are analyzed.