Design 7/10/2018 points): A plan for a one-story structure is shown below. The b
ID: 1839156 • Letter: D
Question
Design 7/10/2018 points): A plan for a one-story structure is shown below. The building is being designed to support a uniform dead load D- 58 psf (including the weight of the steel members) and a nominal uniform live load Lo- 50 psf. Live load reduction information can be found in your equation sheets. (a) Sketch (on the provided figure) the tributary area for girder A. (b) Using LRFD, determine the factored ultimate design moment (M.) for girder A, treating the loads on the girder as distributed loads. Assume girder A is simply supported. (c) Using LRFD, determine the factored ultimate design moment (M.) for girder A, using the load path to determine concentrated loads acting on the girder. Assume girder A is simply supported. 30' 3 25* 25"Explanation / Answer
b)tributary width of girder = (25/2)+(25/2)=25 feet
total dead load = 58 psf
total live load = 50 psf
total factored area load per 1.2D+1.6L combination = (1.2*58)+(1.6*50)=149.6 psf
uniform load on girder=149.6*25=3740 plf=3.74 kip/ft
span of girder=30 feet
maximum moment in girder = 3.74*302/8=420.75 kip-ft
c)tributary width of beams supported by girder A=15'
factored uniform load on each beam = 15*149.6=2244 plf=2.244 kip/ft
force exerted by each beam on girder = 2.244*25/2=28.05 kips
total concentrated load on girder =2*28.05=56.1 kips
maximum moment in girder = 56.1*30/4=420.75 kip-ft