Significance of residual drifts in building earthquake loss estimation

The influence of residual interstorey drifts on economic losses in building resulting from earthquakes is examined. Current building-specific loss estimation methodologies that estimate economic losses based on peak response quantities such as peak interstorey drift ratios or peak floor accelerations are extended to explicitly account for residual interstorey drifts. The new approach incorporates the influence of residual drifts by accounting for the possibility of having to demolish a building as a result of excessive residual interstorey drifts, where the probability of demolition is computed as a function of the maximum residual drift in the building. The proposed approach is illustrated by estimating direct economic seismic losses in four reinforced concrete moment-resisting frame buildings in Los Angeles, California. Two buildings have nonductile detailing representative of pre-1970s building codes, whereas the other two buildings have ductile requirements satisfying current seismic building codes in the U.S. Results indicate that economic losses at intermediate levels of ground motion intensity are often dominated by losses due to residual interstorey drifts. This is particularly true in the case of ductile buildings in which neglecting losses from residual drifts can lead to significant underestimations of economic losses. Copyright (C) 2012 John Wiley & Sons, Ltd.