Question

Problem (42-43) 50 ksi steel, by Calculation: Select the lightest w section for a beam 20 ft in length with a superimposed total uniformly distributed live load of 98 kips and a total uniformly distributed dead load of 50 kips. DO NOT adjust for beam self weight Question 42 Not yet answered Points out of 3.00 P Flag question Lightest W- Select one O a, W24x62 Ob W18x71 O C. W24x55 O d. w12x79

Answer 1

Solution:- Given dater i Dead load (DL) 50 kips, Live Load (LL) 98. kipa Length the beam (L) Now the factored design loads (without self weight) of the given by :- of 20 Ft beam Can be We = 112 (3) + 116 1,61 Wu- 1.2 so at 1.6 3 + 7.84 Wu- Wu= 10.84 kipe/Ft Now the factored ultimate can be given by moment

My = 2- Wu Li 8 2 Mu (10.84) (20) 8 Mu= 542 kips-ft Now the factored mourent strength Com be given by . uchere Фь - 0.9 Also Ob Mn. Mu So, Mn = My Фь 542 0.9 Mn= 602 kips-ft Mn = 6028 12 kipsin ว่า

the X-X Now the section modules about axis can be given by Zx = Mn Fy so Ksi (Given) Fy Zx = 6o2x 1.2 so 144, 48 in we W 1887 from the given table 9.) select the lightest w section which hal Zx = 146 in 3 which is just above 144.48 in. So Selected w section is forfe option W 18 x 7 solution (43 - Lightest w cd 18 inches less) of f

ng L L X IIME 9 option 18 wont sro Р you pleo Elut 8 h chhl a nogo vil mrun club 75l pou plum LL X 90 oor an Zx