LOWER SLOPED ROOF @ ENTRANCE TRIBUTARY SEISMIC WEIGHTS
Item
Tributary Height
Length / Width
% Solid
Area
Unit Weight
Seismic
/ Width
(ft.)
(ft.2)
(psf / lb)
Weight
(ft.)
(kips)
LOWER ROOF
Roof D1-F2
10.0
24.0
100.0
240.0
13.7
3.3
TRANSVERSE WALLS
Wall D1-F1
---
---
100.0
160.0
100.0
16.0
LONGITUDINAL WALLS
Wall D1-D2
8.0
10.0
100.0
80.0
100.0
8.0
Wall F1-F2
8.0
10.0
100.0
80.0
100.0
8.0
TOTAL
35.3
157 KN
Total Seismic Weight =
634.8 Kips (2824 KN)
B-3 Calculate Base Shear
V = CsW
FEMA 302 Eq. 5.3.2
Cs = SDS/R, but need not exceed:
Eq. 3-7
Cs = SD1/TR, but shall not be less than:
Eq. 3-8
Cs = 0.044SDS
Eq. 3-9
Transverse Direction:
Cs = (1.0)/6 = 0.167
Cs = (0.75)/(0.25)(6) =0.5 > 0.167
Cs = 0.044(1.0) = 0.044 < 0.167
V= CsW = (0.167)(634.8 kips) = 106 kips (471 KN)
Longitudinal Direction:
Cs = (1.0)/6 = 0.167
Cs = (0.75)/(0.25)(6) =0.5 > 0.167
Cs = 0.044(1.0) = 0.044 < 0.167
V= CsW = (0.167)(634.8 kips) = 106 kips (471 KN)
B-4 Calculate vertical distribution of seismic forces
The building is analyzed as a one-story structure. The seismic forces to the separate roof areas are
determined by multiplying the tributary weights by the seismic coefficient Cs.
Transverse Direction:
Cs =
0.167
Wroof =
318.99 Kips
Vroof =
53.2 kips (237 KN)
Wlowroof =
108.36 Kips each
Vlowroof =
18.1 kips each (81 KN)
Wsacr =
31.93 Kips each
Vsacr =
5.3 kips each (23.6 KN)
Wentrance =
35.29 Kips
Ventrance =
5.9 kips (26.2 KN)
Longitudinal Direction:
Cs =
0.167
Wroof =
318.99 Kips
Vroof =
53.2 kips (237 KN)
Wlowroof =
108.36 Kips each
Vlowroof =
18.1 kips each (81 KN)
Wsacr =
31.93 Kips each
Vsacr =
5.3 kips each (23.6 KN)
Wentrance =
35.29 Kips
Ventrance =
5.9 kips (26.2 KN)
H3-15
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