w2-7 = 267 plf (3.90 KN/m)
M = wL2/8 = (0.267)(18 ft)2 / 8 = 10.8 kipft (14.64 KNm)
T = M / d = (10.8 / 60 ft) = 0.18 kips (801N)
w7-8 = 286 plf (4.17 KN/m)
M = wL2/8 = (0.286)(10 ft)2 / 8 = 3.58 kipft (4.85 KNm)
T = M / d = (3.58 / 40 ft) = 0.09 kips (0.40 KN)
Longitudinal direction:
The spans act as simply supported elements between the concrete shear walls.
w2-7 = 448 plf (6.54 KN/m)
M = wL2/8 = (0.448)(60 ft)2 / 8 = 202 kipft (274 KNm)
T = M / d = (202 / 90 ft) = 2.24 kips (9.96 KN)
w7-8 = 293 plf (4.27 KN/m)
M = wL2/8 = (0.293)(40 ft)2 / 8 = 58.6 kipft (79.5 KNm)
T = M / d = ( 58.6 / 10 ft) = 5.86 kips (26.1 KN)
Seismic forces to vertical resisting elements from lower sloped roof diaphragm
Transverse direction: The horizontally braced diaphragms are assumed to act as rigid diaphragms
spanning between the steel rigid frames and the end shear walls along lines 2 and 7. Due to the low
stiffness of the moment frames as compared to that of the end concrete shear walls, it is assumed that all
of the shear is distributed to the end walls in relation to their relative rigidities.
Determine relative rigidities of concrete shear walls at ends of low sloped roof area:
H3-21
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