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Reference
CalculationsResult
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This spreadsheet is to be used to check the adequacy of roof purlins for a specified combination of loads. The designis based on the maximum yeild strength (Mn = FySx) as stated in the AISC Manual 13th Ed. This spread sheet can only be used for load combinations with two variables. In most cases the worst case scenario is 0.6DL+W, so this should be adequate. Only the values in the highlighted cells need to be changed. (
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Design for Roof Purlins
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Using an
8" CEE Purlins
with the following properties
Use
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Fy =36ksiFu =55ksi8" CEE Purlins
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Self Weight, sw =
2,92ppfwith tie bars
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Thickness, t =
2,00mm0,07874015748in1,5@ 19 ft 8 in
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Depth, d =
199mm7,834645669in200
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Flange Width, f =
51mm2,007874016in49
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Lip Length, l =
12,0mm0,4724409449in12,5
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Cross Sectional Area, A =
650
mm2
1,007502015in2
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Ixx =3695204,167mm4
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Ixx =8,877763521in4
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Y =99,5
mm me
3,917322835in
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Sx =37137,73032mm32,27in3
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Design Requirements
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ASCE 7-05
Designing for worst case scenario
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2.4.1.7
Wu =
0,9D+1,2W
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Span, L =
21ft0in
Every
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Spacing, s =
4ft0in4 ft 0 in
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Weight of Roof Panels =
10,0psf
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Weight of ceiling panels =
4,2psf
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Dead Load Pressure =
10 + 4,2 = 14,2 psf
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Wind Load =
-50,00psf
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UDL,DL =
(10 + 4,2) x 4 = 56,8 ppf
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UDL,WL =
-50 x 4 = -200 ppf
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WUDL =
(0,9 x -200) + (1,2 x 56,8)= -112 ppf
or-0,11184kpf
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Mu =-6,2k-ft
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Flexural Yeilding Limit State
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 Fy =36ksi
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Mn = FySx =
36 x 2,27 / 12 = 6,8 k-ft
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Ma = Mn/Ωb =
6,8 / 1.67 = 4,07 k-ft
FAIL
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Lateral Torsional Buckling
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The compression flange is continuously braced by the roofing panels,
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therefore, this failure mode is not applicable
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OK
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