Question

PLEASE MAKE SURE YOUR ANSWER MATCHES THE PARTIAL SOLUTION B=2.917"

2) All the members in the following truss have the same square cross section. What is the required cross section dimension if the FS is 3 for buckling and 2.5 for yielding? P = 18 k E = 29,000 ksi Oy = 36 ksi 12 ft G F 16 ft 16 ft 16 ft P P

Answer 1

Solution : Given that Truss. FS = 8 for buckling FiS = 2.5 for yielding E = 29000 ksi, P=18k y = 36ksi B D 1247 A G C 16 ft 1647 Afft 12 O= tant tan' ( z 36.8699 16 At joint A: 1 FAB EFy=0; FAB Sin 36-869 = -18 > FAC FAB 30 kip 18 K (c) EFx = 0; FAB FAB Cos 36.869 FAB = 24 kip (T)

At joint fi FED FCF = 24 K FED = 18 K - 24K FCF 18 K At Joint Go FoGo = 530K cc) Fogy FGF = 24 K (T) FGF 18 kip At joint B FBD FBD = -30 cos (36-869) FBD -24 K (c) T -30k FBC FBC 30 sin 36.869 fee - 18 Me AT Joint Di Fco sim 36.869 +18 sin 36-869 -24K 4 ago - 30 sin 36.869 -0 -30 K Fed 18 K Feo Fo kip

& Tension members are failed by yielding FAC = 24k, FCF = F FG = 24 K FBC = foF = 18K It ť = 18k 30(4,5) Fy (A) 30 (2.5) 36 A = 2.088 in? (it) Compression member are failed by buckling É AB = FOG FOG = 30 kip = 24 kip FBD If pronide, AB = 30 kip Per=FBD = 30 kip TEL 30 FS 1 =16 ft 12 IT 64 4) 30 30 (16 x 1282 5.122 in 2 Therefore, provide a=s.122 in area a naze Adea of cels of member 5.122 in?