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Marc:h 30,2009 <br /> � Ii WA Project No. 2009-030-21 <br /> 3.2 SF.IS�IIC DESICN COIVSIUERATIONS <br /> 3.2.1 General <br /> We understand that thc ncw st�vctures will be designcd in accordance with the 2006 <br /> Intcrnationnl 13uilding Code([BC)standards. For seismic design, the sitc is considered <br /> Site Clnss E,as described in Scction 1613.5.2 of the 2006 [BC. For this sile location,the <br /> design maximum considered spectral response ncccler¢tion at short periods,S�,is 1.169g. <br /> ? '1'he design maximum considered spcotral respo�ise nccelerntion for a l, sccond period,S�, <br /> is 0.409g. <br /> 3.2.2 Suil Liyucfaction <br /> Liquefnction occurs whcn loose,saturated,and relativclycohesionlcss soil deposits <br /> temporarily losc strength because of earthquakc sliaking. �'rimary factors controlling the <br /> dcvclopment of liquel'uciion includc thc iulensily and duration of strong ground motions, <br /> the characteristics of subsurfiicc soils,in-situ stress coiiditions and the deplh to ground <br /> watcr. <br /> The soils undcrlying tlic site consist ofcohesive clt�ys und glnoinlly,consolidnted sunds <br /> und silry sands. hi addition the near surfacc soils arc not satucated ns the ground w�ter <br /> Icvcl at the site is typically ]0 to l 1 lcct below the ground surfacc. for these reasons, <br /> neither the cluys nor thc glucial sand�nre susceptiblc to catil�quakainduced liqucfuction, <br /> and thcrc:fore soil liquefaotion is'not a dcsign considcration for this projcct. <br /> , <br /> 3.Z FOUNDATION DESICN.ItCCOMDIE\UA9'IONS <br /> ` . <br /> 3.3.1 Gencral ' � <br /> Nc understand lhat thc F3R7'tcmiiiial.�4i11 consist of hvo pref�bricutcd bus:helters. <br /> 'I hc.;c shclters arc to measure npproximalely 10 fect widc by A1 feel long nnd wiil Lc <br /> loc;dcd ns shown in the Sitc nnd Exploration plan,Pig�vc 2. In our discussions with the <br /> structural engincer, wc uudcrstond these shelteis will bc supported on isolated squarc <br /> footings. lror ldequate frost protectiou,tlic bus shclter footings shouid be fowidcd nt <br /> lciast 24 inches below finul gradc. <br /> Existing geotechnical dufn indicatcs that the vicinity of thc bus shclters is underlain by a <br /> scrics af soil consisling of npproximntely 4.5 to 6 fcct of undocumented f Il,25 fcet oC <br /> compressible clay, and advance ouhvasli sand. The presence of undocumcnled fill and <br /> compressiUlc clnys bclow the project site requires carcful considerution during dcsign of <br /> i'oundation slniclures. <br /> :ppo.pto�i Dr;m con 4 H WA Gr:oScmdcFa luc <br /> V <br />