Laserfiche WebLink
Helix Design Group,Inc.—Greenwood Heating&Air Conditioning,Everett,WA April 22,2022 <br /> Geotechnical Engineering Report Z0219 <br /> The 2018 IBC considers earthquake shaking having a 2 percent probability of exceedance in 50 years <br /> (i.e. a 2475-year return period), as the code-based design requirement. Using the third-party <br /> graphical user interface tools made available by the USGS at https://seismicmaps.org,MGI derived <br /> the design ground motions to be used for design of the structures. Our evaluation used ASCE 7-16 <br /> as the code reference, Risk Category I/II/III, and Site Class D-Stiff Soils. The results of our <br /> evaluation are provided in Table 2 (below): <br /> TABLE 2 <br /> SEISMIC DESIGN PARAMETERS <br /> Parameter Value Basis <br /> Site Class D-Stiff Soils Table 20.3-1 of ASCE 7-16 <br /> Ss 1.398 seismicmaps.org <br /> Fa 1.0A seismicmaps.org <br /> SMs 1.398 =Fa•Ss,2018 IBC Eqn.16-36 <br /> SDs 0.932 =2/3 SMs,2018 IBC Eqn.16-38 <br /> S� 0.498 seismicmaps.org <br /> Fv 1.8 B.c 2018 IBC <br /> SMi 0.896 B.c =Fv•Si,2018 IBC Eqn.16-37 <br /> SDi 0.598 B•C =2/3 SMi,2018 IBC Eqn.16-39 <br /> PGA 0.604g seismicmaps.org <br /> PGAM 0.665g seismicmaps.org <br /> To --c Not applicable <br /> Ts --c Not applicable <br /> Ti. 6 sec. seismicmaps.org <br /> Notes: <br /> A. Use the value provided unless the simplified design procedure of ASCE 7 Section 12.14 is <br /> used. If this occurs,please contact our office for more information. <br /> B. Based on Table 1613.2.3(2)of the 2018 IBC—An ASCE 7-16 Chapter 21 analysis has not been <br /> performed. <br /> C. More detailed seismic design criteria are available upon request. Please contact MGI's office <br /> for more information. <br /> 3.6 Liquefaction Potential <br /> Liquefaction is a sudden increase in pore water pressure and a sudden loss of soil shear strength <br /> caused by shear strains, as could result from an earthquake. Research has shown that saturated, <br /> loose,fine to medium sands with a fines(silt and clay)content less than about 20 percent are most <br /> susceptible to liquefaction. Our explorations did not encounter any extensive deposits of poorly <br /> consolidated sandy soil, and we do not anticipate that site soils will liquefy during a large-scale <br /> seismic event. <br /> Migizi Group,Inc. Page 6 of 16 <br /> rnwiz� It.4j <br />