Acceptance Criteria: Acceptance criteria for each performance objective are prescribed for each

analytical procedure in Chapter 6 and numerical values for each of the criteria are given in

Chapters 7 through 10.

3. STRUCTURAL DESIGN CRITERIA. The basic lateral and vertical seismic-force-resisting systems

considered here are diagonal strap configurations (Panels A1, A2, and D1) in Appendix B. These are

considered bearing wall systems. The format of Table 5.2.2 of FEMA 302 is used in Table 3-1 to present

the response modification coefficient, R and deflection amplification factor, Cd. These values are used to

calculate the base shear, and design story drift. The system overstrength factor, Ω0 used in FEMA 302 is

not included here because shear panel overstrength is accounted for by Ω0QE in Equation C-16. This is

the maximum lateral capacity of the shear panel based on the maximum estimated ultimate stress of the

panel diagonal straps.

The response modification coefficient, R in the direction under consideration at any story shall not exceed

the lowest value for the seismic-force-resisting system in the same direction considered above that story

excluding penthouses. Other structural systems (dual systems) may be used in combination with these

cold-formed steel panels, but then the smallest R value for all systems in the direction under

consideration must be used for determining the loads applied to the entire structure in that direction. Dual

systems must be used with caution, particularly if differences in stiffness result in interaction effects

(FEMA 302, 5.2.2.4.2) or deformation compatibility problems (FEMA 302, 5.2.2.4.2). Another structural

system may be used in the orthogonal direction with different R values, and the lowest R value for that

direction only shall be used in determining loads in that orthogonal direction.

Deflection

Basic Seismic-

Response

System Limitations and

Modification Amplification Building Height Limitations (ft)

Force-Resisting

Factor, Cd

System

Coefficient,

by Seismic Design Category

R

B

C

D

E

F

Bearing Wall Systems

Cold-Formed Steel

Shear Panels with

4

3

NL

NL

65

65

65

Diagonal Strapping

4. DEFLECTION AND DRIFT LIMITS. The design story drift, ∆ shall not exceed the allowable story

drift, ∆a as obtained from Table 3-2 (FEMA 302, Table 5.2.8), for any story. The design story drift shall be

computed as the difference of deflections at the center of mass at the top and bottom of the story under

consideration, as determined by Equation C-29 (FEMA 302, Eq 5.3.7.1). For structures with significant

torsional deflections, the maximum drift shall include torsional effects. All portions of the structure shall

be designed and constructed to act as an integral unit in resisting seismic forces unless separated

structurally by a distance sufficient to avoid damaging contact under total deflection, δx, as determined by

Equation C-29, (FEMA 302, 5.2.8).

Structure

Seismic Use Group

I

II

III

Structures with diagonal strap

0.020hsx1

shear walls

0.015hsx

0.010hsx

1

hsx is the story height below level x.

3-3

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