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Causes of a "fatal flaw?"

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Two studies published at attempt to
explain the fundamental causes of the failure of the "pre-Northridge
connection." (Please scroll down until you see the heading: New Steel
Buildings as Flawed as the Old Ones?)

The term "pre-Northridge connection" was coined after many unexpected
fractures were found in the connection between steel beams and
columns following the 1994 earthquake in Northridge, California. By
that time, thousands of steel building using this connection detail,
which has now been called "fatally flawed," had been constructed on
the west coast of the United States and elsewhere during the previous
30 years.

The cracks so shocked the engineering community that the California
Seismic Safety Commission asked for, and received, an emergency
withdrawal of the building code provision that authorized
construction of the "pre-Northridge connection."

This development prompted the Federal Emergency Management Agency to
fund $12 million worth of studies to improve the seismic performance
of steel buildings. (Links to these studies are available on the same
web page.)

Meanwhile, other researchers sought to identify the problem's
fundamental causes.

The reasons for this important structural problem may be revealed in
two studies written by Dr. Ralph Richard, a retired professor and
expert in finite-element material stress analysis. He was asked to
supply this research to the above referenced web site because use of
that knowledge may help save lives during coming major earthquakes.
Gil Davis, Associate

Center for Investigative Reporting, Inc. (
CIR produces PBS FRONTLINE documentaries and other journalistic publications
131 Steuart St., Suite 600, San Francisco, CA 94105-1238
Voice: 415-543-1200, x305; Fax: 415-543-8311

Home office phone and fax: 650-364-7769

CIR's Mission: To foster justice, democratic values and
accountability by conducting and promoting media investigations of
underreported issues in the public interest.

Read what top structural engineers are doing to correct a "fatal
flaw" found in many steel-framed buildings that could prompt them to
during a massive earthquake.
Go to:

See how tilt-up, concrete construction can collapse in an earthquake
yet be economically strengthened to withstand higher seismic forces.
This popular form of construction houses a large proportion of our
country's industry and high-tech firms.
Go to:

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