12 Select the lightest available section if Fy 50 ksi P40 k

12. Select the lightest available section if Fy 50 ksi. P-40 k P 40 k Lateral bracing is provided at each of the concentrated loads as well as at the ends of the span. Obtain CS from the AISC manual. W 1.0 k/ft

Solution

C_b for the beam will be equl to 1 between point load locations.

design moment of beam = moment at midspan of beam = (40*10)+(1*30²/8)=512.5 kip-ft

unbraced length of beam = 10 ft

therefore, lightest beam that has moment capapcity of 512.5 for unbraced length of 10 ft is W21x68 which has a capapcity of 531.6 kip-ft for unbraced length of 10 ft