Application of Mean Spectral Matching of Time Histories

Date: 4/25/2019

Time: 02:00 PM

Room: Pine

Performance-based design of buildings requires development of one or more suites of acceleration time-histories modified to result in response spectra (RS) that individually or in the aggregate are similar to a target RS. A method of modifying time histories such that the mean of the ground-motion suite matches the target spectrum was introduced by Mazzoni et al., in 2012 and has now been expanded upon and implemented in practice in a number of projects in California. The method has been approved by peer review panels for the aforementioned California projects in such a way that the suite of spectra does not suffer the 10% penalty implemented in ASCE 7-16 on time histories that are tight-spectral matched (where each record is modified to match the target spectrum). The reasoning for the penalty in ASCE 7-16 is that tight spectral matching modifies the time histories to a point that they have lost their original waveform characteristics and because the suite of time history spectra all collapse onto the target so that the record-to-record and period-to-period variability and dispersion of the as-recorded suite is lost. The method of mean spectral matching avoids these problems by slightly modifying each time history such that the average of the suite of spectra matches the target spectrum, which is the goal of modification of time histories to meet building-code standards. The method of mean spectral matching can be applied to a multitude of different types of target spectra such as Uniform Hazard Spectrum (UHS) and Conditional Mean Spectrum (CMS). The method can also be applied to the current codes that apply the method of making the average of a suite of time history spectra meet a certain target requirement such as ASCE 41-13, 41-17, 7-10, 7-16, and codes that reference those. We have applied it by matching the average of RotD100, SRSS, and Fault Normal spectra of suites ranging from 7 to 11 time histories. The objective of this paper is to describe the method and provide examples of how it is applied to engineering projects to meet building-code requirements.

Presenting Author: Kenneth S. Hudson

Authors