CHAPTER 4
(a) To provide minimum design criteria for
APPLICATION OF CRITERIA
structures appropriate to their primary function and
use considering the need to protect the health, safety,
4-1.
General.
and welfare of the general public by minimizing the
earthquake-related risk to life, and
a.
Performance Objectives.
Seismic
performance objectives for a building are defined by
(b) To improve the capability of essential
a desired performance level for the building (e.g.,
facilities
and
structures
containing
substantial
damage state or ability to perform an essential
quantities of hazardous materials to function during
function) when subjected to a specified seismic
and after design earthquakes. The design earthquake
hazard (i.e., deterministic or probabilistic ground
ground motion levels specified here could result in
motion). A performance objective for each of the
both structural and nonstructural damage. For most
four Seismic Use Groups (Table 4-1) is prescribed in
structures designed and constructed according to
the
following
paragraphs.
The
performance
these Provisions, structural damage from the design
objectives (Table 4-4) are derived from appropriate
earthquake would be repairable, although perhaps not
combinations of three performance levels (Table 4-
economically so.
For essential facilities, it is
3), and two design ground motions.
expected that the damage from a design earthquake
would not be so severe as to preclude continued
b.
Basis of Provisions.
occupancy and function of the facility. The actual
ability to accomplish these goals depends upon a
(1) Performance Objective 1A. All buildings
number of factors, including the structural framing
governed by this document are required to comply
type, configuration, materials, and as-built details of
with Performance Objective 1A, which is intended
construction.
For ground motions larger than the
to protect life safety for Ground Motion A, defined
design levels, the intent of these Provisions is that
as
two-thirds
of
the
Maximum
Considered
there be a low likelihood of structural collapse."
Earthquake (MCE). The Acceptance criteria for the
performance objectives require compliance with the
(2)
Enhanced performance objectives.
NEHRP
Recommended
1997
edition
of
the
Performance levels and performance objectives
Provisions for Seismic Regulations for New
prescribed in this document are generally based on
Buildings and Other Structures (FEMA 302). The
guidance provided in SEAOC Vision 2000.
The
following are excerpted from Chapter 1 of those
acceptance criteria for the enhanced performance
provisions:
objectives and the nonlinear analytical procedures are
adapted from FEMA 273.
"These provisions present criteria for the
design and construction of structures to resist
c.
Analytical Procedures.
Minimum
earthquake ground motions. The purposes of these
requirements for the analytical procedures associated
provisions are as follows:
4-1
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