combination of performance levels from Table 4-3
Use Groups. Performance Levels 2 (Safe Egress) and
with an appropriate ground motion.
As indicated
3 (Immediate Occupancy) are enhanced performance
above, Performance Objective 1A (Life Safety) is
levels for Seismic Use Groups II and III.
The
required of all seismic use groups, and the other
Collapse Prevention performance level indicated in
objectives in Table 4-4 pertain to buildings in
Table 4-3 is an assumed ultimate response level for
Seismic Use Group II or III.
structural components and is not an applicable design
performance level.
The physical significance of
these performance levels is indicated in Figures 1-1
4-10. Minimum Requirements for Analytical
and 1-2.
Procedures.
Minimum analytical procedures for the various
4-8.
Design Ground Motions.
performance objectives associated with each of the
seismic use groups are indicated in Table 4-4. The
As indicated in Table 4-4, two ground motions,
analysis procedures are described in Chapter 5, the
derived from the MCE, are considered in this
acceptance criteria for each of the procedures are
document, and their derivation is discussed in
prescribed in Chapter 6, and the numerical
Chapter 3. Ground Motion A is the basic ground
acceptance limits for the various structural systems
motion in the FEMA 302 provisions; it is
are provided in Chapter 7. Note that for Performance
approximately equivalent to 10 percent probability of
Objective 1A, FEMA 302 provisions are prescribed
exceedence in 50 years, and is the ground motion
with appropriate R factor and an Importance Factor,
associated with Performance Level 1 (Life Safety) for
I, equal to 1.0. For enhanced performance objectives,
all seismic use groups. Ground Motion A is also used
more severe ground motion and/or more restrictive
with Performance Level 2 to provide Performance
acceptance criteria are prescribed in lieu of the R or I
Objective 2A (Safe Egress) for Seismic Use Group II,
factors.
while Ground Motion B is used to provide
Performance Objective 2B (Safe Egress) for Seismic
Use Group IIIH and Performance Objective 3B
4-11.
General Design Procedures.
(Immediate Occupancy) for Seismic Use Group IIIE.
Note that while "Safe Egress" is used to describe the
a.
Performance Objectives 1A (All Buildings).
performance level in both Performance Objectives
Table 4-5 provides a step-by-step tabulation of
2A and 2B, different ground motions and acceptance
procedures for the analysis and design of buildings,
criteria are used to comply with the two performance
in accordance with FEMA 302, to comply with
objectives.
Performance Objective 1A (Protect Life Safety).
Reference is made to applicable sections in FEMA
4-9.
Performance Objectives.
302 and to corresponding paragraphs in this
document.
Additional guidance pertaining to the
The seismic performance objectives for the various
total design process is provided in Chapter 2. The
seismic use groups in Table 4-1 consist of the
analyses and design procedures for this performance
4-9
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