| An approach for systematic determination of the optimal cost-effective aseismic design for reinforced concrete frame-wall buildings is proposed. Optimal target reliabilities for damage control and life safety are determined through minimization of the respective life-cycle costs with a constraint on the risk of death. The process requires the proper integration of probabilistic seismic hazard analysis, structural damage and reliability assessments, fatality rate estimation, and life-cycle cost formulations. The resulting target reliabilities can be translated into conventional terms such as required design base shear coefficients to insure damage control and collapse prevention.; For the minimum life-cycle cost design, the cost functions for the initial cost, damage repair cost, contents loss, injury and fatality losses, and indirect regional economic losses are formulated in terms of structural damage and probability of collapse. The repair cost function is derived based on actual repair cost data, and the indirect loss is computed using the input-output model of the regional economy. The cumulative life-cycle damage costs are then obtained in present value with a random point process model of the occurrences of future earthquakes and the appropriate seismic hazard curve.; Development of the methodology requires the quantification of structural damage under all possible earthquake loadings, according to the Park-Ang damage index, as well as the quantitative relations between the computed structural damage and the direct and indirect losses. The Park-Ang damage index model is extended to reinforced concrete structural walls. For structural damage and reliability assessments under uncertainties, a simplified Monte Carlo simulation procedure for stochastic ground motion generation and nonlinear random time-history response analysis is developed.; The methodology is applied to a class of buildings, modeled by a 5-story, ductile moment-resisting reinforced concrete structure with structural walls, which is assumed to be located on a soft soil site in Tokyo. For the class of buildings illustrated in the study, the optimal design base coefficient appears to be equal or close to the current value required by the building code for Tokyo. |
