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CR LAURENCE Z-SERIES GLASS CLAMPS (03/27/2014) Page 5 of 19 <br /> Clamp Strength: <br /> Screws holding clamp back to front: two#10 SS screws into tapped holes. <br /> an=0.75*67.5ksi*0.0175 in2= 886#each <br /> Ts=¢Tn/1.6= 886/1.6=551/t <br /> Total allowable service tension load on bracket=2*554#= 1,108# <br /> Check screw shear strength <br /> Screw strength,Av=0.0175 int,Fut=33.7 ksi <br /> Vs=0 Av Fav/1.6 =0.65*.0175*33.7/1.6 =240# <br /> Total allowable service shear load on bracket=2*240#=480# <br /> Shear carried by through glass pin in clamp: <br /> Pin strength,Av=0.0767 in2,Fnt=33.7 ksi <br /> Ts= 0 Av Fm,/1.6 =0.65*0.0767*33.7/1.6 = 1,050# <br /> Pin strength will not control clamp loading <br /> FOR LARGE SERIES CLAMPS (2-1/8"TALL) <br /> Moment on screw from vertical load <br /> My= V*1.469" <br /> Screw tension from EM and solving for T <br /> Tv=Mv/(2.125"/2) = 1.469V/1.0625"= 1.382V <br /> setting Tv=Ts and solving for V <br /> V= 1,050#/1.382=780# (for all large clamps) <br /> Vertical load will not be limiting for any of the clamp styles or attachments. <br /> Clamp connections to posts: <br /> Moment on anchor screw from horizontal load <br /> MH= H*1.48" <br /> Screw tension from EM and solving for T <br /> TH=MH/(BC/2) = 1.469H/(Bc/2) =2.938H/Bc <br /> Bc= clamp width <br /> Bc= 15/16"for 1/4" glass <br /> Bc= 1-3/32"for 3/8"glass (1.09/0.935) = 1.166 <br /> Bc= 1-7/32 for 1/2" glass (1.21/0.935) = 1.294 <br /> Determine allowable horizontal loads based on the allowable screw tension load <br /> Solving for H: <br /> H=TH*BC/2.938 <br /> Substituting for TH=Ts= 1,050# <br /> MH= 1,050*Bd2.938 =357.4*Bc <br /> Clamp base secured to post with 5/16"fastener <br /> Screw secured with rivet nut for thin wall post or tapped hole for sch 40 pipe. <br /> EDWARD C.ROBISON,PE <br /> 10012 Creviston Dr NW <br /> Gig Harbor,WA 98329 <br /> 253-858-0855/Fax 253-858-0856 elrobison@narrows.com <br />