Question

2.5 Select two back-to-back 10 in. deep C-sections (A-36 Steel) with 3/8” gusset plates for the following conditions. (10 points) Tension Load: D = 60 kips L = 80 kips W= 100 kips Member Length: L = 25 ft. Wind load deflection limit: Aw < 1/8 in. Note: Specify the size and spacing of filler plates.

Answer 1

Solution Given that i 10 in. Deep C-section (A-36 steel) 3/8" gusser plates Tension load : Dead load Đ= 60 kips Live load L = 80 kips . Wind load w = 100 kips Memben length 2 =25ft* Wind load deflection limit : awal in Design load = 1-2D+w+ = 1-2160) +80 +100 Factored Design load Tu = 252 Kips Grade a stell - A36 . Fy = 36 tisi, Fu = 58 ksi Steph: Yeilding in 98053 Section : Pe Ta = d Fy Ag =0.98 36 x Ag 252 = 32.4 Ag Ag = 252 Ag = 7.78 mm2 Elfective Area (A ) = U Am [ U = 0.85 Assumed =0.85 An I

in Desigre Strength q Net section De Tn = Qe fute = 0.15 X58X0.85 A = m 5.8 A . A = 252 36.98 A e = 6.78 mm² The required area is (max of Ag, Ac) = 7.78 mm² Therefore, sedect 2c 10x15.3 from the code book member details Gross ara section Ag = 5.96 in 2 Radius 4 gyration Armin = 3.87 in The member connecied to web. Step 2: Design Strength : Yeilding in gross section : ... Design strength of gross section . PETR = Qe Fy Ag = 0.9 X 36 x 8.96 = 290.3 kips Fracture in net section Effective are Aez UAG = 0.85*8.96 He = 7.616 in

(4 Design strength of net section de. En = de Fute - 0.75 X 58 X 7.616 = 331-3 kips Therefore, the design strength of member is smallest 4 (290.3 kips, 331.3 kips) = 0 Th = 290.3 kips Checking - Tu = 252 kips cd Tn = 2903 kips. Therefore, the connection is safe. Checking slenderness: L = 25x12 .. 3.87 . Ley = 77.52 < 300 v Hence, wery is in the Linnit of slendrress.