The estimation of MDOF nonlinear structural response given an earth-quake of magnitude M at distance R is studied with respect to issues such as the benefits and harms of (1) first scaling the records, (2) selecting records from the “wrong” magnitude, (3) alternative choices for how to scale the records, and (4) scaling records to a significantly higher or lower intensity, etc. We find that properly chosen scaling can reduce the necessity of the number of nonlinear analyses by a factor of about four, and that proper scaling does not introduce any bias. Several global and local nonlinear damage measures are considered. A five-DOF model of a steel structure is used; other cases are under study. The paper finishes with a demonstration of the use of such results in the estimation of the annual probability of exceeding a specified interstory ductility (drift) or other damage measures.

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SUMMARY This study focuses on the development of vulnerability functions for tall buildings. A systematic simulation approach based on the Pacific Earthquake Engineering Research loss assessment framework is used to develop building vulnerability functions that provide estimates of losses to buildings under ground motions of various intensities. The steps involved in the procedure are: quantifying ground‐motion hazard using a vector of spectral accelerations; predicting building response parameters such as story drifts, floor accelerations, and residual drifts under the quantified hazard; accounting for structural collapse and demolition; and predicting story‐wise losses and total building loss using the building response information. Emphasis is placed on capturing the effects of epistemic and aleatory uncertainties in random variables, such as ground motions, structural response parameters, loss costs, etc., to quantify the uncertainty in the final loss estimate. The risk assessment approach is used for developing vulnerability functions for six tall buildings, namely, 20‐story and 40‐story steel moment resisting frame buildings based on 1973 and 2006 codes, a 42‐story concrete core wall building and a 42‐story concrete dual system building. The vulnerability functions are used to perform loss assessments for individual buildings assumed to be located in Los Angeles. The vulnerability and the loss assessment procedures are illustrated in detail for the 2006 20‐story steel moment frame building, and a summary of the final loss estimates are provided for all other buildings. It is seen that epistemic uncertainties in both ground motion hazard and building vulnerability cause significant epistemic uncertainties in the loss assessment results. Copyright © 2012 John Wiley & Sons, Ltd.

As part of the PEER Center's tall building initiative (TBI) project, practicing engineers designed three structural systems, each based on commonly used codes and guidelines in addition to the guidelines developed by PEER. The designs were analyzed by three research teams, using a set of 75 ground-motion pairs, to predict response parameters for evaluating the performance of tall buildings. This study focuses on analytically estimating the seismic losses to these buildings to assess their relative seismic performance. The loss assessment process follows a comprehensive simulation approach which takes into account several random variables such as building response, repair costs, etc. Throughout this study, epistemic and aleatory uncertainties in the random variables are accounted for, in order to quantify those in loss estimates. Based on the dollar loss results, the performance of the dual-system building is compared and contrasted with that of the other building systems considered in the PEER study.

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