Evaluating the Impact of Spectrum-Matched Time Histories on Biased FRS Estimates: Part 2-Adequacy Analysis Using Enhanced Spectrum-Matched Time Histories

Floor response spectra (FRS) are critical for the seismic analysis of the nuclear secondary system as per American Society of Civil Engineers Standard 4-16. Despite the use of spectrum-matched time histories, significant variations in FRS estimates can lead to inaccuracies in seismic analysis and system design. Our companion article explored the influences of ground-motion parameters modification due to spectral matching on FRS accuracy using machine learning, revealing that changes in spectral acceleration and damping scaling factor index I_DSF for damping ratios ξ = 7%, ξ = 2%, and ξ = 10%, significantly contributed to biased FRS estimates. Building on these insights, we propose enhanced spectrum-matched time histories that include additional I_DSF values for different damping ratios. Using a nuclear service building as a case study, we demonstrate that these enhanced time histories significantly improve FRS accuracy, benefiting seismic safety practices in the nuclear industry.