c. Preliminary building design (Following steps in Table 4-5 for Life Safety). The preliminary design of the
building follows the steps outlined in Table 4-5 for Performance Objective 1A. The design is then updated to meet
the enhanced performance objectives laid out in Table 4-6 for Performance Objective 2A.
A-1 Determine appropriate Seismic Use Group. The structure falls into Seismic Use Group II.
A-2 Determine Site Seismicity. The site seismicity for this example from the MCE maps is:
SS = 1.50g S1 = 0.75g.
A-3 Determine Site Characteristics. The soil for this example site is assumed to correspond to site class D.
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 coefficients are:
Fa = 1.0
Fv = 1.5
SMS = FaSS = (1.0)(1.5g) = 1.50g
SM1 = FvS1 = (1.5)(0.75g) = 1.13g
SDS = 2 / 3S MS = 2 / 3(1.5g) = 1.0g
SD1 = 2 / 3S M1 = 2 / 3(1.13g) = 0.75g
For regular structures, 5-stories or less in height, and having a period, T, of 0.5 seconds or less, the design
spectral acceleration need not exceed:
SDS ≤1.5Fa = (1.5)(1.0) = 1.50g > 1.0g
SD1 ≤0.6Fv = (0.6)(1.5) = 0.9g > 0.75g
A-7 Select structural design category. From Tables 4-2a and 4-2b for Seismic Use Group II and the design
spectral response accelerations:
Seismic Design Category = Da
Seismic Design Category = D
Footnote ` 'requires that structures with S1 ≥ 0.75g be assigned to Seismic Design Category E.
A-8 Select structural system. The lateral system consists of a combination of special concrete shear walls and
intermediate steel moment frames. In the transverse direction, the structure has concrete shear walls at the
ends and moment frames in the interior. Longitudinally, concrete shear walls resist the lateral forces.
The upper roof diaphragm consists of metal decking that acts as a flexible diaphragm. The metal deck
diaphragm spans are less than 2:1 in accordance with the limits for diaphragm span and depth set forth in
Table 7-24. The lower roof diaphragm in the longitudinal direction consists of horizontal pipe bracing that
transfers the shear from the suspended upper concrete shear walls to the exterior shear walls.
A-9 Select R, Ω o & Cd factors.
Transverse (North-South): Building frame system with special reinforced concrete shear walls:
Longitudinal (East-West): Building frame system with special reinforced concrete shear walls: