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Structural <br /> Engineering & Design Inc. <br /> = 1815 Wright Ave La Verne, CA 91750 Tel:909.596.1351 Fax: 909,596,7186 <br /> By: Bob S Project: Fast Signs Project#: 24.0917-16 <br /> BEAM Contiguratlon:TYPE A SELECTIVE RACK <br /> RMI Section 5.2, PT II <br /> Section <br /> Beam= SpaceRak SB376M 3.75 in x 0.06 in <br /> Ix=Ib= 1.253In-4 2.50In <br /> Sx= 0.627 inA3 <br /> t= 0.060 in E= 29500 ksi 1.63 in <br /> Fy=Fyv= 55 ksi F= 300.0 <br /> Fu=Fuv= 65 ksi L= 108 in <br /> Fya= 59.0 ksi Beam Level= 1 1,625 in <br /> P=Product Load= 3,400 lb/pair <br /> D=Dead Load= 30 lb/pair 3.750 in <br /> 1. Check Bending Stress Allowable Loads 0.060 In <br /> Mcenter=F*Mn= W*L*W*Rm/8 <br /> W=LRFD Load Factor= 1.2*D + 1.4*P+1.4*(0.125)*P RM12.2,item 8 <br /> FOR DL=2%of PL, <br /> W= 1.599 <br /> Rm= 1 -[(2*F*L)/(6*E*Ib+3*F*L)] _•- <br /> 1 -(2*300*108 in)/[(6*29500 ksi*1.253 InA3)+(3*300*108 in)] ;-7. <br /> ,� , <br /> = 0.797 <br /> if F= 0.95 P�e•d uak <br /> Then F*Mn=F*Fya*Sx= 35.13 in-k <br /> Thus, allowable load -per beam pair=W= F*Mn*8*(#of beams)/(L*Rm*W) Beams+ <br /> 35.13 in-k*8* 2/(108in *0.797* 1.599) Length <br /> = 4,084 lb/pair allowable load based on bending stress <br /> Mend= W*L*(1-Rm)/8 <br /> _ (4084 lb/2)* 108 In * (1-0.797)/8 <br /> = 5,596 in-lb @ 4084 lb max allowable load <br /> = 4,6591n-lb @ 5400 lb imposed product load <br /> 2. Check Deflection Stress Allowable Loads <br /> Dmax= Dss*Rd <br /> Rd= 1-(4*F*L)/(5*F*L+ 10*E*Ib) Allowable Deflection= L/180 <br /> = 1-(4*300*108 in)/[(5*300*108 in)+(10*29500 ksi*1.253 inA4)] = 0.600 In <br /> = 0.756 In Deflection at imposed Load= 0,570 in <br /> if Dmax= L/180 Based on L1180 Deflection Criteria <br /> and Dss= 5*W*LA3/(384*E*Ib) <br /> L/180= 5*W*L^3*Rd/(384*E*Ib*#of beams) <br /> solving for W yields, <br /> W= 384*E*I*2/(180*5*L^2*Rd) <br /> = 384*1.253 in^4*2/[180*5*(108 in)^2*0.756) <br /> = 3,577 lb/pair allowable load based on deflection limits <br /> Thus, based on the least capacity of item 1 and 2 above: Allowable load= 3,577 lb/pair <br /> Imposed Product Load= 3,400 lb/pair <br /> Beam Stress= 0.95 Beam atLevell <br /> �".Z- <br />