by W. Holmes, T. Anagnos, L. Cluff, R. Olson, A. Porush and E. Schwartz
Holmes, W., T. Anagnos, L. Cluff, R. Olson, A. Porush and E. Schwartz (1993). Expected Seismic Performance of Buildings (Invited Paper). SMIP93
Seminar on Seismological and Engineering Implications of Recent Strong-Motion Data, p. 55 - 76.
Click on the link below for the full text:
Tens of millions of us spend much of our lives in the buildings and structures where we work,
reside, worship, and go for entertainment, relaxation, or medical care. Local and state
government elected officials and administrators adopt and enforce the codes and standards
governing the design and construction of these buildings. Insofar as building safety is
concerned, these codes are the "law of the land." The seismic design provisions of the codes
are especially important to the performance of buildings in areas subject to earthquakes. We
have a right to know how the buildings we occupy will perform in earthquakes.
The Earthquake Engineering Research Institute, a national professional organization dedicated
to improved earthquake resistant design, prepared this document. Its purpose is to help policymakers,
code administrators, and others involved in the design, construction, and building
maintenance processes understand how the seismic design provisions of the codes, knowledge
and practices of our architects and engineers, and quality of construction affect the thousands
of buildings of various types, sizes, and designs that we use daily. This paper attempts to
establish expected levels of damage for buildings built to the 1991 Uniform Building Code (UBC
9 I), under various earthquake conditions.
First, we must dispel a myth: There is no "earthquake-proof' building. Although we are
continuously improving our understanding of earthquakes and how buildings perform, there are
limitations to building codes. Many older buildings were not built for earthquake resistance, and
codes do not apply to many aspects of construction and use. As a result, we must expect losses
from future earthquakes. These losses may take many forms: total or partial collapse due to
shaking and ground failures, interior damage to nonstructural systems and elements, and damage
to contents and equipment. While failures receive great media attention, we are heartened by
the greatly improved performance of newer buildings constructed to recent building codes. But
even new buildings are not immune to damage. Given the wide range of building types, site
conditions, and earthquake characteristics, the performance of all building, even new ones, will
not be the same. Many new buildings may suffer damage in a major earthquake, and a few
should be expected to suffer serious damage.
The following sections cover the most important aspects that influence building safety. They
include a discussion on earthquake causes and the accompanying shaking, fault rupture, and
other ground failures. A brief summary is provided of common strategies for reducing
earthquake hazards through planning, locating structures, and regulating construction. Building
codes will be described in detail and the expected earthquake performance of new buildings built
to the UBC 91 or older unreinforced masonry buildings retrofit to the 1991 Uniform Code for
Building Conservation (UCBC) will be discussed. Initially, damage estimates have been limited
to buildings in UBC Zone 4, because of the high probability of seismic events and the
corresponding interest in this kind of information in this zone.