Question

A simply supported beam loaded by two forces is shown in the figure. Select a pair of structural steel channels mounted back to back to support the loads in such a way that the deflection at midspan will not exceed 1/2 in and the maximum stress will not exceed 15 kpsi. Use superposition. In the figure, F1 = 450 lbf and F2 = 300 lbf. Use Table A-7 to select the smallest Imperial units channel that meets the requirements, where dimension a corresponds to the channel length. F1 F2 6 ft 4 ft 10 ft C UAB The pair of channels that should be selected is in long and its weight capacity is bf/ft.

Answer 1

Guswer Draw F. B.D. m .450 tbf Bookbook B hokoft**k dottaa Take moments about Ĉ Rolo) – 450(14) – 300(10) = 0 → RO = 465 lb.. . { fyzo Ro + RC = 450 + 300 → RC = 4501300 – 465 = 285 lbf Moment at A is given by MA = 465(6812) = 33480 lbf-in MB = 46566X12.) +(465-450 (4x12) =34-200 lbf-in

긋 ET Omax = Mmox (Given, Cmax = 15kpsi) → 15x10= 34200 .. Z = 2.28 in from deflections, use beam 5 and 6f Table A-9 | Ytx=to = Face (47a"-224) - Bruce → -0.5 = 450(72)6120) (120772-246) 6C30X10C) 1240) 300(2403) 48630906I > I = 1206 ina I = 6.3 int from table A-Z Choose two 5 in-6.7 lbl/4t channels I = 2(749) = 14.98 int z = 2(3.) = 6 inS Ores

midspan = () = -0.421 in . Amidspan = 20:421 in Ans Omax = 34.2 = 5.7 kpsi .. to mox = 5.7 kpsi pou Good Luck