921 105TH PL SE 2022 Plans 2022-11-08

Diaphragm Stiffness Calculation The diaphragm stiffness will be calculated based on the methodology from"Post Frame Building Design", by John N.Walker and Frank E.Woeste. This method is widely accepted in the post frame industry for determining metal diaphragm stiffness. 1. The diaphragm stiffness,c'=(Ext)/[2x(1+u)x(g/p)+(K2/(bxt)2) Where: c'= 3130 lbs/in=Diaphragm stiffness of the test panel(1992 Fabral Test for Grandrib III) E= 2.75E+07 psi=Modulus of elasticity for metal sheathing t= 0.017 in=Steel thickness for 29 ga metal sheathing u= 0.3 =Poisson's ratio for steel g/p= 1.085 =Ratio of steel corrugation pitch to steel sheet width b= 144 in.=Length of test panel K2= - =Sheet edge purlin fastening constant(unknown) 2.The diaphragm for the same metal for a different length b can be calculated with the above above equation once the constant K2 is known. Solving for K2 yields: K2=[((Ext)x(bxt2))/c]-[2x(1+u)x(bxt)2x(g/p) K2= 878 in4 3.The stiffness of the acutal panel will be calculated from equation in 1.above,based on its actual length,b' Roof pitch= 4 /12 Building width= 21 ft 0= 18.43 °roof angle b'= 132.82 in=length of steel roof panel at the given angle for 1/2 of the roof c= 2670 lbs/in-stiffness of actual roof diaphragm 4.Calculate the equivalent horizontal roof stiffness,ch for the entire roof ch= 2xcx(cos28)x(b'/a) Ch= 5,066 lb/in a= 126 in.post spacing 5. Calculate the stiffness,k,of the post frame,which is the load required for the top of the frame a distance,d For d=1",k=P=(6xdxEpx1p)/L3 d= 1 in-deflection used to establish k l = 108 in4-Momentof inertia of post Ep= 1.10E+06 psi-Modulus of elasticity of post L= 108 in-Bending length of post k= 566 lbs/in 6.Determine the side sway force,mD from tables based on k/ch verses number of frames. NF= 3 frames in building(including end walls) k/ch= 0.1117 mD= 0.95 =calculated stiffness of metal roof diaphragm • Since roof sheathing is wood, mD used for calculations is 1.00 Page 5 of 13