SPECIFICATION FOR THE DESIGN OF - Transcon Steel

Commentary on the Prescriptive Method for One and Two Family Dwellings - 2004 69
Sum of Weights
For Base Shear, Vertical Distribution and Shear Wall Design:
At Roof: 27,540 + 3,750 + 5,040 = 36,330 lb
At 2 nd Floor: 15,000 + 7,500 + 10,080 = 32,580 lb
Sum: 36,330 + 32,580 = 68,910 lb
30’
P
For Diaphragm Design
50’
P Roof = 36,330 – 3,150 = 33,180 lb
P 2nd Floor = 32,580 – 6,300 = 26,280 lb
30’
P Roof = 36,330 – 1,890 = 34,440 lb
P 2nd Floor = 32,580 – 3,780 = 28,800 lb
P
Determine Base Shear – SDC D2
Base Shear, V = C s W (IBC Eq. 16-34)
C s = S DS /R
S DS = 1.17
(IRC Table R301.2.2.1.1)
R = 6
(IBC Table 1617.6, System 1-K)
C s = 1.17/6 = 0.195
V = (0.195)(68,910) = 13,437 lb
Vertical Distribution
F x = C vx V (IBC Eq. 16-41)
C vx =
WxH
x
n
(IBC Eq. 16-42 with K = 1)
W H
∑
i
i=
1
n
∑ F i
I = 1
i
V x = (IBC Eq. 16-43)
Height 2nd = 9’ + 1’ = 10 ft
Height Roof = (2)(9) + 1 + ½(7.5’) = 22.75 ft
Diaphragm Weight Height Weight x Height C vx F x
(lb) (ft)
(lb)
Roof 36,330 22.75’ 826,508 0.7173 9,638 9,638
2 nd Floor 32,580 10’ 325,800 0.2827 3,799 13,437
Total 68,910 1,152,308
V x
(lb)