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15.4 Strucural Design Requirements DK BARBER RCE 21,110 12/28/2011 Seismic Coefficients for nonbuilding structu es not similar to buildings pg 3 of 4 table 15.4-2 select mechanically anchored flat bottom R= 3 12.7.2 Effective Seismic weight W,=Total DL+Total LL(operating weight,assume tank's contents at 90%full) W,= 4,716 LBS 15.7.6 Ground-Supported Storage Tanks fo Liquids 15.7.6.1 Fundamental Period? eq.12.8-7 Total V=0.30 DSWI p V=0.30 x 0.61 x 4,424 x 1.5= 1,287.5 Ta =Cth'n AST Only Vns-r=V=0.30 x 0.61 x 1,123 x 1.5= 386.2 from table 12.8-2 All other structural Contents Only Vn,ents V=0.30 x 0.61 x 3,301 x 1.5= 901.3 C,= 0.02 systems x= 0.75 15.4.2 Small tank not anchored tre t as rigid per Section 15.4.2 of this standard h= 3.04 Ta = 0.046 ,as Ta is<0.06 s V=0.30 SDSWlp eq.15.4-5 Overturning Moment apply at AST cg where V,s7= 386.2 where Vcontenn= 901.3 1287.5 =Total seismic base shear heighf of co, seismic My D AST =V- x 1.51 ft = 386.2 x 1.51 = 581 seismic My LL =V__x 1.45 ft = 901.3 x 1.45 = 1,307 C of CC rotipping edge where M,,,,i= 1,888 CG,= 1888/1287 1.47 resist M8 =W,x CG„ = 4,716 x 1.54 = 7,263 f.s.= 7263/1888= 3.85 Sliding without anchorage No problem Check if Sliding Compare frictional re istance vs.V although eastward and southward movement is blocked 15.7.6.1.5 V<W.tan 300 V<4,71 x 0.577 V<2,721 max seismic base shear shall not exceed 1,287 vs 2,721 f.s.= 2721/1287= 2.11 No problem What happens if horizontal m vement during major earthquake? Won't tip over if AST slides westward, pavement is at same elevation(see photo). Block wall prevents eastward travel. Flotation: Empty Weight= 1,415 lbs Footprint(SF)= 26.95 Bouyant at 0.84 FT if AST Empty. Flotation due to flooding is n a concern at this location,tank could float if water was 0.84 FT deep and AST empty. Re iew of FEMA Map does not suggest flooding in less than 100 year event.