A ground motion selection and modification method capturing response spectrum characteristics and variability of scenario earthquakes

Earthquake ground motion variability is one of the primary sources of uncertainty in the assessment of the seismic performance of civil systems. The paper presents a novel method to select and modify ground motions to achieve specified response spectrum variability. The resulted ground motions capture the median, standard deviation and correlations of response spectra of an earthquake scenario conditioned on a specified earthquake magnitude, source-to-site distance, fault mechanism, site condition, etc.The proposed method was evaluated through numerical analyses of a 20-story RC frame structure. The example demonstrated the excellent capacity of the proposed method in capturing the full distribution of nonlinear structural responses under a specified scenario. In particular, a suite of 30 or 60 records selected using the refined algorithm can lead to statistically stable results similar to those obtained from a much larger set. The proposed algorithm is computationally efficient. It shows great potential in the performance-based earthquake design of nonlinear civil systems.