1-ft = 0.30m
Design Members (use HSS w/ Fy = 46ksi, or 317.2MPa):
Per paragraph 7-3.b (3), the effective out-of-plane unbraced length is equal to two thirds of the total length.
Therefore;
KL = (2/3)18.6'= 12.4'or 149" (3.78m)
KL 1000
h
110
≤
≤λp =
Per AISC seismic provisions;
r
t
Fy
Fy
KL Fy
149" 46ksi
r≥
=
= 1.01 - in (2.57mm)
Therefore;
1000
1000
110
λp =
= 16.2
ksi
46
Try TS 4X4X1/4;
From AISC column load tables for an effective length KL = 13'
φc Pn = 68k > 3.21k (302.5KN > 14.3KN) = Pu
O.K.
φt Pn = 0.9(46ksi )3.59 - in2 = 149 k > 3.21k (662.8KN > 14.3KN)
O.K.
O.K.
r = 1.51" > 1.01" = rreq'd
h/t = 16 < 16.2 = λp
O.K.
Choose TS 4X4X1/4 (TS101.6mmX101.6mmX6.35mm)
(4) Chord/Collector Elements (High Roof).
Determine Design Loads:
Seismic;
Note: Only Chord/Collector elements in the plane of the braced frames will be designed for
Chord/Collector elements perpendicular to the braced frame are a part of the transverse moment frames.
From the static analysis, the axial loads were determined as follows;
Maximum Chord Force = 73-lb (0.32KN)
Maximum Collector Force = 788-lb (3.51KN)
(governs)
By inspection with the design for the low roof, a W12X14 is adequate.
Choose W12X14 (W304.8mmX0.204KN/m)
H4-23
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