Document: NUREG-0800
Document ID: 5c405a7a-1098-462c-b352-0353348123fd
Document Type: srp
Title: 3.05
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1235/ML12352A305.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.50
CFR Part: 
CFR Title: 

Content:
have been computed for each of these three records individually and then the average horizontal spectrum computed by (lognormally) averaging the two horizontal spectral accelerations for each damping value considered frequency by frequency. From these sets of three, individual bin averages have been computed for damping ratios of 2 percent, 3 percent, 5 percent, 7 percent and 10 percent. Spectral ratios were then computed relative to the 5 percent damped spectra. The spectral ratios were then smoothed using a 9-point running average smoothing algorithm. The results of this process are presented and compared in the following. The NUREG/6728 record set is binned by both magnitude and distance as well as for both rock and soil site categories. The magnitude bins are defined as magnitude 5 to 6 (M55), magnitude 6 to 7 (M65) and magnitudes greater than 7 (M75). Distance bins are typically defined as from 00 to 10 kms (000010), 10 to 50 kms (010050), 50 to 100 kms (050100) and 100 to 200 kms (100200). In addition to magnitude, distance and site binning, the record sets associated with NUREG/CR-6728 are also categorized into Western US (WUS) and Central and Eastern US (CEUS) record sets. The WUS data set is composed of empirical recorded motions while the CEUS data set is primarily composed of modified WUS recordings attempting to account for differences in source and site parameters WUS to CEUS. Average spectral ratios were computed for each of these bin categories. Tables 1 through 4 present averages for CEUS-Rock, CEUS-Soil, WUS-Rock and WUS-Soil site categories. It should be noted that the data tables of spectral ratio generally refer to horizontal spectra only. It was found that the spectral ratios for vertical motions in the data sets were essentially the same as those of the corresponding horizontal ratios. In Table 1, the spectral ratios for the gross bin averages for EUS Rock sites are listed for spectral ratios of 2% to 10% damping. Similarly, Tables 2 through 4