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Calculating Seismic Forces <br />From 2006 International Building Code, ACE 7-05 <br />generic calx <br />Shear (lateral movement) <br />V <br />W <br />$os = 2/3 SMs <br />V = 0.30SDs W I <br />1 = Importance Factor <br />F, <br />SMs = F.Ss <br />Max SDs = 2/3 Max SMs <br />Max V = .30(M ax SDs) W I <br />Overturning <br />h= <br />Overturning moment = V'h/2 <br />Resisting moment due to weight of tank and contents = <br />W'w/2 <br />Assume uplift = 2/3 V <br />then effective weight = W - 2/3V <br />Resisting moment due to weight of tank and contents = <br />(W - 2/3V)`w/2 <br />generic calcs continued <br />Including Friction in shear calculation <br />p = Coefficient of Friction <br />Fr = Friction Force <br />N = normal force = W <br />F,= VN <br />then Fr= p(W-2/3V) <br />Net base shear = V - F, <br />p = 0.45 for concrete - steel <br />Net base shear = V - .45'(W -2/3V) <br />Note friction will not be considered in seismic <br />calculations for this site <br />Units <br />Comments <br />lbs Base Shear <br />lbs Non bldg structure operating weight - tank & contents <br />Equation 11.4-3 <br />lbs Sections 15.7.6 a. And 15.4.2 <br />IBC Section 1604.5 --not a bldg that represents substantial <br />hazard to human life in event of failure, and not bldg <br />designated as essential facility <br />Short period site coefficient (at 0.2 period) <br />(11.4-1) <br />ft lbs <br />ft Its <br />ft lbs Weight of tank and contents times 1/2 width <br />Ib <br />Ib <br />ft lbs <br />