A ground motion selection and modification method through stratified sampling

Abstract

In this article a ground motion selection and modification (GMSM) method is presented, suitable for the probabilistic seismic assessment of the damage state and collapse potential of building structures. The objective is to predict the probability distribution of the engineering demand parameters in a future earthquake event, provided that the spectral acceleration at the fundamental period of the structure is given. The GMSM method uses a vector-valued intensity measure that incorporates the Normalized Spectral Area parameter. Through stratified sampling on the Normalized Spectral Area, optimised ground motion suites are formed. Its advantage over other GMSM methods is that it implicitly matches the multivariate distribution of the response spectrum in the region of the structure elongated period, and it adopts an unbiased estimator of the response central tendency. The GMSM method is applied in the probabilistic response assessment of a first-mode dominated multi-degree-of-freedom system that represents a ten-storey building. Substantial reduction in the computational work is achieved, compared to another method.