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ANDERSON & ASSOCIATES CONSULTING ENGINEERS, INC. <br />3902 VtLLA SAN JOSE DRIVE, JACKSONVILLE, FLORIDA 32217 (904) 731-7978 Fax (904) 731-7771 <br />12"x 12" TOWER SECTION <br />STRUCTURAL CAPACITY <br />4. Check 3/16" Weld at 3/8" Gusset Plate <br />__©_1316 <br />MD LP:=PO <br />5.813 <br />-+0.813 in. <br />2 <br />Lp = 3.72 in. <br />tw := 0.1875 in (3/16" Weld) <br />Determine Allowable Force At Chord Member <br />Pp := Fw-Lp·0.707·tw·4 Pp = 9.861 kips <br />5. Determine Tower Height, Lc = KL, where Global Buckling Becomes a Consideration <br />Since the Weld at the Chord to End Members Controls the Compressive Pew <br />Fcw:= -Capacity of the Tower Section <br />Al <br />Fcw = 7.45 ksi <br />At Tower Heights, Lc, Where Fa < Fcw, Global Buckling Will Control the Compressive Capacity of the Tower <br />Lc:= 51000·rx <br />4 Few <br />2 1 <br />12 Le = 34.475 ft rx = 5 in <br />Therefore,at Tower Heights < Le = 34.475 ft Pa:= Fcw-A3 Pa = 31.8 kips <br />at Tower Heights > Lc = 34.475 ft, Global Buckling Will Control <br />Now determine allowable axial stress for various unbraced lengths <br />51000Fa(Le):=- ksi Pa(Lc):= Fa(Lc)·A]kips Fa(360) = 9.838 30 ft Pa(360) = 42.0 kip/T \ 2 <br />Fa(420) = 7.228 35 ft Pa(420) = 30.9 <br />Fa(480) = 5.534 40 ft Pa(480) =23.6 <br />Fa(540) = 4.372 45 ft Pa(540) = 18.7 <br />Fa(600) = 3.542 50 ft Pa(600) = 15.1 <br />Fa(660) = 2.927 55 ft Pa(660) = 12.5 <br />Fa(720) = 2.459 60 n Pa(720) = 10.5 <br />in