Optimal retrofit for a school under seismic hazard including risk assessment

ABSTRACT The paper proposes a formulation to select the optimal retrofit strategy for a damaged school under seismic hazard, by applying risk and reliability assessment techniques. The formulation considers the cost-effectiveness of alternative retrofit strategies, including failure consequences, to get adequate balance (CE: Balance is an uncountable noun) between the costs and the gains on reliability. The proposed alternatives should produce a failure probability below the target value, which is obtained by minimising the present value of the expected life-cycle cost. The failure consequences include the potential life loss, injuries, expenditures due to off-campus resumption of classes and loss/damage of contents. Exceedance of the shear force and bending moment capacities and the allowable inter-story drift are the considered limit states. A relationship between the cost and the increment on reliability is proposed and calibrated for the case study; MCS is applied to calculate the failure probabilities. An example of a two-story building is a school located in the Tlaxcala State; for this case, the target failure probability is 1.6 × 10−4. The optimal retrofit strategy is the one that corresponds to the minimum expected life-cycle cost. The proposal may serve to generate risk, reliability and resilience-based retrofit recommendations for schools under seismic hazard.