Design beam B15. The beam has the compression flange fully braced. Select an eff
ID: 1765928 • Letter: D
Question
Design beam B15. The beam has the compression flange fully braced. Select an efficient W Section (ASTM A992). The uniform service dead load does not include the self weight of the beam. Account for the Cb factor in the design, if appropriate. The member is simply supported and the live load deflection limit is L/360 and the gravity load (live load and dead load) is L/240. Show that the beam designed meets all the AISC moment and deflection requirements. (45 Pts)-SHOW ALL WORK Weight of insulation Weight of metal deck Weight of shear studs Weight of HVAC Miscellaneous dead loads Weight of occupants Weight of Snow -3 PSF - 5 PSF -2 PSF - 6 PSF - 10 PSF 20 PSF - 15 PSF Q2-Would you use the same section for B22? Why?(5 points)Explanation / Answer
Total dead load=3+5+2+6+10=26 psf
Live load=20 psf
Snow load=15 psf
The LRFD load combination that would govern strength design is 1.2D+1.6(Lr or S)
Since Lr is greater than S, 1.2D+1.6Lr is the governing load combo
Factored area load=1.2*26 + 1.6*20 =63.2 psf
Tributary width of beam B15=4'9"=4.75 ft
Uniform load on beam=63*4.75=300 plf=0.3 kip/ft
Span of beam=14.67 ft
Maximum moment in beam=0.3*14.67²/8=8 kip-ft
Required beam size from strength standpoint=w8x10
Service level area load=26+20=46 psf
Uniform load on beam=46*4.75=204.7 plf=0.017 kip/in
Span of beam=14.67 ft=176 in
Deflection of beam due to total load=(5/384)*0.017*176?/(29000*30.8)=0.238 in
L/240=176/240=0.73 in
Therefore, required section is w8x10
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