A TARGETED NONLINEAR DYNAMIC PROCEDURE TO EVALUATE THE SEISMIC PERFORMANCE OF STRUCTURES

The Targeted Nonlinear Dynamic Procedure is introduced to offer a practical evaluation of the seismic performance of structures. Building upon the SAC/FEMA closed- form probabilistic framework it can incorporate all important sources of variability and can be calibrated for conservatism. The hazard curve is combined with the nonlinear dynamic analysis performed for each limit-state using one or two levels of the intensity measure. This is either the elastic first-mode spectral acceleration or the more sufficient inelastic spectral displacement. From the suite of ground motion records only targeted subsets are used that are optimally selected to estimate the median and dispersion of the structural response. The simple factored demand and capacity checking format employed allows for a seamless inte- gration with current engineering practice, while rational safety factors add the required de- gree of conservatism to account for epistemic uncertainties both for ductile and brittle modes of failure. Using a four-story reinforced concrete frame as an example, the proposed ap- proach is shown to provide a relatively simple means to account for important sources of var- iability in nonlinear response history analysis. It offers powerful analysis options to a knowledgeable user in a format that can be upgraded incrementally and can provide an ex- cellent introduction to sophisticated analysis techniques with more precisely controlled levels of conservatism.