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U TR BLOCK, INC. <br />77 <br />SEISMIC SLIDING <br />The target factor of safety for seismic is 75% of the static value. Live loads are ignored in the analyses <br />based on the basic premise that the probability of the maximum acceleration occuring at the exact same instant as <br />the maximum live load is small. <br />Details are only shown for sliding at the base of blocks, a check is made at the foundation level with the <br />answer only shown. <br />The vertical resisting forces is W1 + W1 + Pav + Paev SumVs = 5471 <br />Resisting force = SumVs * tan(phi) + intercept x L FRe =3673 ppf <br />Driving force = Pa_h + Pae_h + Pif <br />=1110 +110 +200 FDr =1420 ppf <br />FOS = FRe/FDr [leveling pad / foundation] FoS =2.59 / 3.19 <br />SEISMIC OVERTURNING <br />Overturning is rotation about the front toe of the wall. Eccentricity is also a check on overturning <br />Resisting Moment = M1 + M2 + MPav + MPaev <br />Driving Moment = MPav + MPaeh +MPif <br />Factor of Safety = SumMrS/SumMoS <br />SEISMIC BEARING <br />Bearing is the ability of the foundation to support the mass of the structure. <br />Qult = c*Nc + q*Nq + 0.5*gamma*(B')*Ng <br />where: <br />Nc = 50.59 <br />Nq = 37.75 <br />Ng = 56.31 <br />c = 0.00 psf <br />q = 195.00 psf <br />Calculate Ultimate Bearing, Qult (seismic) <br />eccentricity (e) <br />Equivalent Footing Width, B' = L - 2e + Ivl pad <br />Bearing Pressure = sumVs/B' + 213' + LP depth)/2 * LP depth <br />Factor of Safety for Bearing = Qult/Bearing <br />SumMrS =13033 ft ppf <br />SumMoS = 4169.96 ft ppf <br />FoS = 3.13 <br />Qult = 21860.43 psf <br />e =0.838 <br />B'=4ft <br />sigma =1442 psf <br />FoS =15 <br />UltraWall 4.0.16287.0 Page 12 <br />