Question

Select the lightest adequate W-section with a nominal depth of 14 in or less, for a 34ft. beam with a total uniformly distributed load of 1000 lb/ft. Select the beam based only on bending stress then check to see if deflection is O.K. LL Allowable deflection = L/360 TL Allowable deflection = L/240 Fb = 2/3 FY Fy = 50,000 lb/in2 LL is 70% of total load. No figure given.

Find

M _max =

Sr =

Selection =

delta LL allow =

delta LL max =

and is

Deflection O.K.?

Answer 1

ginen, WT= 1000 lblft 70% WT WL = 700 elft 300 lblft Wu 1.2 WoT 1.6 WL 2 1.2x300+ 1.6X700 Wo 1480 lblft 1480X34 Mu = Wool OXIOS 213.86 kip-t 8 WI4826 Now, select d = 13.91 > IX = 245inch SX = 35.3 inch 3 Fy- 50X10 To = 33.33 KS) 2 fo - x 50X10 For My I M Sy = M = 33.33435-3 M = 98.05 kip-ft Not sattisfied Now, use wl4x68, Weight of Bears = 61. Ablft klu = \. 2x ( 300+68) + 1.6x you Wu = 1561.6 lblft Mu Wul? = 225.65 kip it 8

For W 14868, d=14, Sx = 103inch, Ix="123 incht M = fox Sx M 33.33 % 103 12 M2 286.08 Kip-ft 8. Muz 0.94286.08 16. Ma = 257.47 Kip-ft d. Mo My That's OK wet STL= 384 EI STL= 5 Х 1000x (34x12) 4 128 723x 29000X103 384 STL = 1.43 inch 3 4X12 =1. Tinch >STL Cok, Allowable TL, S = 240 240 4. Now, Sil= 5 -X 384 700x(34X12) 12x 29 000 X16X723 Si= 1 inch L Allowlable S: 360 SE 34x12 366 = 1.13 Inch > SLL (OK)