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J`'I i�lilUl��i 4:���';�;! Si�l\�, i����. <br />0.001 timcs thc ���all hcight (a braccd condition), static, at-rest, latcral carth pressures should bc <br />uscd. Thc cquivalent fluid wcights of nati��c and imported fill for both thc acti��c and at-rest <br />appa�ent earth pressure conditions arc presentcd in thc tablc below. All of thc valucs in the table <br />arc based on the assumption that proper long-terni drainage is provided, and that no buildup of <br />hydrostatic pressurc occurs. Pigure G presents the apparent earth pressure diagram for a multipic <br />braccd wall. <br />Ittemporary soil nail walls are uscd to shorc thc excavation, �ve rccommend that the permancnt <br />basemcnt wall design bc based on the active, apparent carth pressure listed in the table. If a top- <br />down permanent soil nail wall is installed, we recommend that the structural en��inecr evaluate <br />�vhether thc activc or the at-rest apparent carth pressure is most appropriate. <br />"l�hc table bclow also presents active and at-rest equivalent fluid ���cights (tri:mgul:u� <br />disu•ibutions); thcsc valucs may bc uscd for buricd permancnt walls on thc sitc that do not h;���c <br />multiple braces (iloors) but :u'c single-braced or amtile��ered, or �vhere large distances occur <br />bctwccn pcnnanent �eail supports. Nc widcrstand that thcrc may bc cascs whcrc thc upper <br />portion (30 !0 3_i fcet) of thc garagc �eall is cantilcvcrcd and thc lowcr portion has multiplc <br />braces. In that case, wc rccommend that the appropriatc triangular distribution be applied for the <br />c:mtilever purtion of the wall and the appropriate apparent carth pressure bc uscd in the multiplc <br />bracc portion of thc wall. �Vc also rccommcnd that the top of thc multiplc Uracc portion havc thc <br />full app:irent earth pressure applied (no truncation). In these and olher Iess certain configurations <br />Shannon R\Vilson should re��ic��� thc proposcd pcnnancnt wall pressure diagrams. <br />The total eanh pressures should be analyzed for scismic loading conditions using a d��namic load <br />increment equal to a percentage of the s[atic, active and at-rest earth forces. The percentage <br />incrcascs for hoth the notive and importcd fill soil cases and for both the active and at-rest earth <br />pressure conditions are presented in the table below. This percent load increment should be <br />applied as a unifomi load to thc �eall, with thc resultant force acting at the midpoint of the �vall <br />hcight. r\ perccntagc load incrcasc for scismic conditions is consistent with a pscudostatic <br />an:ilysis using thc Mononobc-Okabc cquation Cor lalc�al carth pressures and a horizonlal scismic <br />coefficient of O.15�. The scismic coefficient is not necessarily equivalent to the site peak ground <br />accelcration. The peak ground acceleration is expericnccd only a few times within the record of <br />carthquakc sh:iking, and thc actual carthquakc ground motion is cydic in namrc, not static. <br />V':ilucs �,( thr scismic cocfficicnt :irc thus t���icall�• onothird to onahalf the valuc of thc pcak <br />,, �,.�..�.�.,�,�, 'I-1-09Ga�3-OOi <br />I' <br />