SPECIFICATION FOR THE DESIGN OF - Transcon Steel

54 Commentary on the Prescriptive Method for One and Two Family Dwellings - 2004
The equation does not give a real number for box-beam headers. This is an indication
that the given box-beam header assembly (2-800S162-43) is inadequate for the given
loading conditions (without intermediate stiffeners).
E3 Back-to-Back Header Design
Calculate the maximum allowable spans for a 2-800S162-43 back-to-back header supporting
an opening located on the first floor of the two-story building described in Section E2. All
referenced equations and sections are to the Specification unless noted.
E3.1 Design Loads
Dead Loads:
Ceiling Dead Load = 5(24/2)
Roof Dead Load = 7(24/2)
Wall Dead Load = 10(8)
Top Floor Dead Load = 10(24/2)
Soffit Dead Load = 2(7)
Total Dead Load
Live Loads:
Roof Live Load = 16(28/2)
Snow Load = 0.7(50)(28/2)
Top Floor Live Load = 30(24/2)
= 60 plf
= 84 plf
= 80 plf
= 120 plf
= 14 plf
= 358 plf
= 224 plf
= 490 plf
= 360 plf
E3.2 Load Combinations
1. 1.4D = 1.4(358) = 501 plf
2. 1.2D + 1.6L + 0.5(L r or S) = 1.2(358) + 1.6(360) + 0.5(490) = 1,251 plf
3. 1.2D + 0.5L + 1.6(L r or S) = 1.2(358) + 0.5(360) + 1.6(490) = 1,394 plf controls
E3.3 Member Properties
H = 8.0”
t = 0.045”
R = 0.09375”
I xx = 9.21 in 4
E3.4 Bending Capacity
M n = 3,166 ft-lb
Φ b = 0.95
Φ b M n = 6,016 ft-lb
2
wL
M =
8
L =
L = 5.88 ft = 5’-10-1/2”
E3.5 Deflection Limit
∆ = L/240 (total loads)
Web depth
Design thickness
Inside bend radius
Moment of inertia
Unfactored nominal moment capacity (calculated per Specification)
Resistance factor for bending strength (per Specification)
(for two sections, punched)
8M
w
=
8(6,016)
1,394
The deflection equation for a simply supported span with distributed load is: