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Parameter value <br />N4apped Sp€ctral Acceleration at 0.2 sec Period Ss 1.487 <br />N4apped Sp€ctral Acceleration at 1.0 sec Period Sr <br />Site Class <br />Site t'lodified Spectral Acceleration at 0.2 sec Period Sus 1.487 <br />Site Modified Spectral Acceleration at 1,0 sec Period Snr 0.821 <br />Design Spectral Acceleration at 0.2 sec Period Sos 0.991 <br />Design Spectral Acceleration at 1.0 sec Period Sor 0.547 <br />copy of the Design Response Spectrum, as generated by the USGS application is also included in <br />App€ndix E. Based on this output, the following parameters may be utilized for the subject site: <br />2013 CBC SEISMIC DESIGN PARAMETERS <br />'The 2013 CBC requires that Srte Class F be assigned to any profile containing soils vulnerable to potential failure or collapse under <br />seismic loading, sud) as liquefiable soils. For Site Class F, the site coefftoents are to be determined in accordance with Section 11.4.7 <br />of ASCE 7-10. However, Section 20.3.1 of ASCE 7-10 indicates that for sites with structures having a fundarnental period of vibraton <br />equal to or less than 0.5 seconds, the site coefficient factors (F" and F") may be determined using the standard procedures. Itre <br />seismic design oarameters tabulated above were calculated usino the ste coefficient factoB for Sate Class D. assumino that the <br />fundamental penod of the slructure is less than 0.5 seconds. However, the results of the liquefaction evaluabon indicate that the <br />subiect site is underlain by potenbally liquefiable soils. Therefore, if the proposed structure has a fundarnental period greater than <br />0.5 seconds, a site specific seismic hazards analysis would be required and addibonal subsurface exploration would be necessary. <br />Groulld llotiollPa ra meters <br />For the purposes of the liquefaction analysis performed for this study, we utilized a site <br />acceleration that is consistent with maximum considered earthquake ground motions/ as <br />required by the 2013 CBC. The peak ground acceleration (PGAI4) was determined in accordance <br />with Section 11.8.3 of ASCE 7-10. The parameter PGAM is the maximum considered earthquake <br />geometric mean (MCE6) PGA, multiplied by the appropriate site coefficient from Table 11.8-1 of <br />ASCE 7-10. The web-based soft\^,are application U.S. Seismic Desion Maos (described in the <br />previous section) was used to determine PGAM, using ASCE 7-10 as the building code reference <br />document. A portion of the program output is included as Plate E-2 in Appendix E of this report. <br />As indicated on Plate E-2, the PGAM for this site is 0.545q. An associated earthquake magnitude <br />was obtained from the 2008 USGS Interactive Deaggregation application available on the USGS <br />website. The deaggregated modal magnitude is 6.96, based on the peak ground acceleration <br />and NEHRP soil classification D. <br />The Seismic Hazards Map for the Tustin. California 7.5 Minute Ouadranole. published by the <br />California Geological Survey (CGS), indicates that the subject site is within a liquefaction hazard <br />zone. Therefore, the scope of this investigation included a detailed liquefaction evaluation in <br />order to determrne the site-specific liquefaction potential. <br />Liquefaction is the loss of strength in generally cohesionless, saturated soils when the pore- <br />water pressure induced in the soil by a seismic event becomes equal to or exceeds the <br />overburden pressure. The primary factors which influence the potential for liquefaction include <br />Y,,iiilili <br />Proposed rybn Sign - Santa Ana, CA <br />Project No. 16G208-1 <br />page 9 <br />o.547 <br />Liouefaction