1601 N Bristol St - Phase 1 - Plan

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Mr. Amir Houriani Project No. 32-6235-00 1601-1607 N. Bristol Street August 29, 2022 The Deaggregation program yielded a mean magnitude (MW) of 6.61 for the liquefaction potential evaluation was performed using a magnitude 6.61 earf ground acceleration of 0.612g. CITY OF SANTA ANA Planning and Building Agency Y " S. PageA►pproved FOR PERMIT ISSUANCE Master ID: , the Based on criteria set forth in CGS Special Publication SP117A, a factor of safety against the occurrence of liquefaction greater than about 1.3 can be considered an acceptable level of risk where high -quality, site -specific penetration resistance and geotechnical laboratory data is collected. Seismic settlement calculations are included in this report. Results of the liquefaction analysis are summarized below: Return Period Peak Ground Acceleration (g)(') Moment Mean M �Mw�ude Factor of Safety Total Liquefaction Settlement in 475 ears 0.612 6.61 1.3 0.50" NOTES: 1) From U.S. Seismic Design Maps website: https:Hseismicmaps.org 2) From USGS Deaggregation website: https:Hearthguake.usgsgov/hazards/interactive//hazards/interactive/ The seismically induced settlement was calculated to be 0.50 inches. Because one boring was used to evaluate the potential for liquefaction, the estimated seismic -induced differential settlement was taken as two-thirds of the total seismic settlement, yielding approximately 0.33 inches. California Building Code Seismic Parameters For determination of the seismic ground motion parameters, site classification is required. In accordance with Section 20.3.1 of ASCE 7-16, the site would fall under Site Class F due to the presence of soils susceptible to liquefaction. A site response analysis in accordance with Section 21.1 of ASCE 7-16 would be required; however, Section 20.3.1 provides the following exception: "For structures that have a fundamental period of vibration equal to or less than 0.5 sec, a site response analysis is not required to determine the spectral accelerations for liquefiable soils. Rather, a site class is permitted to be determined in accordance with Section 20.3." The fundamental period of vibration for the proposed building has not been provided to our firm by the structural engineer; however, based on our experience with similar projects, structures of four stories or less typically exhibit periods less than 0.5 seconds. Site classification was determined based on the criteria set forth in Section 20.3 of ASCE 7-16 and in accordance with the 2019 California Building Code (2019 CBC). The average field standard penetration resistance was calculated to be approximately 19 blows/ft. In accordance with Table 20.3.1 of ASCE 7-16, an average standard penetration resistance of 15 to 50 blows/ft corresponds to Site Class D; therefore, the classification of the project site corresponds to Site Class D. n �u A.G.I. Geotechnical, Inc. • 16555 Sherman Way, Suite A • Van Nuys, CA 91406 11 Office: (818)785-5244 • Facsimile: (818)785-6251