and the 1.0 second ordinates for Ground Motion A or

B, or for the MCE. The calculation of the effective

(2) Linear Static Procedures.

damping is estimated as follows:

(a)

Displacement-dependent device.

The

∑W

Linear Static Procedure (LSP) may be used to

implement

displacement-dependent

energy

i

(8-18)

4*π *k

dissipation devices, provided that the following

requirements are satisfied:

where *$ *is the damping in the framing system, and is

set equal to 0.05, unless modified. *W*j is work done

1. The ratio of the maximum resistance in

by device *j *in one complete cycle corresponding to

each story, in the direction under consideration, to the

floor displacements ***i, the summation extends over

story shear demand calculated using Equations 5.3.4-

all devices *j*, and *W*k is the maximum strain energy in

1 and 5.3.4-2 in FEMA 302, shall range between 80

the frame, determined using Equation 8-19.

percent and 120 percent of the average value of the

ratio for all stories. The maximum story resistance

shall include the contributions from all components,

1

∑ Fi di

(8-19)

elements, and energy-dissipation devices.

2 i

2. The maximum resistance of all energy-

where *F*I is the inertia force at floor level I, and the

dissipation devices in a story, in the direction under

summation extends over all floor levels.

consideration, shall not exceed 50 percent of the

resistance of the remainder of the framing, where said

(b) Velocity-dependent devices.

resistance

is

calculated

at

the

displacements

anticipated in the MCE. Aging and environmental

1. The LSP may be used to implement

effects shall be considered in calculating the

velocity-dependent

energy-dissipation

devices,

maximum resistance of the energy dissipation

provided that the following requirement is satisfied:

devices.

The maximum resistance of all

3.

The base shear and story forces

energy-dissipation devices in a story, in the direction

calculated by Equations 5.3.4-1 and 5.3.4-2 in FEMA

under consideration, shall not exceed 50 percent of

should be reduced by the damping modification

the resistance of the remainder of the framing, where

factors in Table 8-2 to account for the energy

said resistance is calculated at the displacements

dissipation (damping) affected by the energy

anticipated in the MCE. Aging and environmental

dissipation devices.

Figure 8-8 indicates how the

effects shall be considered in calculating the

response spectrum is modified by the damping

coefficient *B*s and *B*1 in Table 8-2. In Figure 8-8, the

spectral ordinates *S*xs and *S*x1 represent the 0.2 second

8 - 32

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