Building design (following steps in Table 4-5 for Life Safety). The design of the building
c.
follows steps outlined in Table 4-5 for Performance Objective 1A.
A-1 Determine appropriate Seismic Use Group. Per Table 4-3 of the manual, the building is allowed
to incur moderate structural damage. Therefore, it is a standard occupancy structure with a Seismic Use
Group of I.
A-2 Determine Site Seismicity. The site seismicity for this example from the MCE maps is assumed
as:
Ss = 1.40g, and S1 = 0.50g.
A-3 Determine Site Characteristics. For the purpose of this problem, a stiff soil condition was
assumed corresponding to a site classification of ` lass D'per Table 3-1 of the manual.
C
A-4 Determine Site Coefficients, Fa and Fv. From Tables 3-2a and 3-2b for the given site seismicity
and soil characteristics, the site response coefficients were interpolated as follows:
Fa = 1.00
(Table 3-2a)
Fv = 1.50
(Table 3-2b)
A-5 Determine adjusted MCE Spectral Response Accelerations:
SMS = Fa(SS) = 1.00(1.40) = 1.40
(EQ. 3-1)
SM1 = Fv(S1) = 1.50(0.50) = 0.75
(EQ. 3-2)
A-6 Determine Design Spectral Response Accelerations:
SDS = (2/3)SMS = (2/3)1.40 = 0.93
(EQ. 3-3)
SD1 = (2/3)SM1 = (2/3)0.75 = 0.50
(EQ. 3-4)
The approximate period of the structure (based on T = 0.1N, where N = number of stories) is:
Tapprox = 0.1N = 0.1(3) = 0.3 < 0.5
(EQ. 5.3.3.1-2 FEMA 302)
Since Tapprox < 0.5, and because the structure is less than 5 stories in height, Equations 3-5 and 3-6 must be
checked in the short period range:
SMS [ .5Fa
1
(EQ. 3-5)
SM1 [ .6Fv
0
(EQ. 3-6)
Therefore,
SMS = 1.4 < 1.5(1.00) = 1.5
SM1 = 0.75 < 0.6(1.50) = 0.9
Use SDS = 0.93, & SD1 = 0.50
A-7 Determine Seismic Design Category. With SDS = 0.93, SD1 = 0.50, and a Seismic Use Category
of I, enter Tables 4-2a and 4-2b to obtain a Seismic Design Category of ` '
D.
A-8 Select Structural System.
Gravity: Reinforced concrete hollow core slabs to span between transverse bearing walls.
Lateral: As permitted by table 7-1 of the manual;
Transverse direction:
Special reinforced concrete shear walls.
Longitudinal direction:
Special reinforced concrete moment frames.
A-9 Select R, ς, & Cd factors.
o
H2-8
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