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RE: Progressive Collapse Design - Brian McDonald

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The report mentioned by Brian McDonald was one of a series of reports that
came out of a project I headed at the National Bureau of Standards (now the
National Institute of Standards and Technology) in the mid 70's.  The
project looked at aspects of design adopted in Europe following the Ronan
Point collapse and prospects for U.S. practice.  The report mentioned by
Mr. McDonald has not been updated.  The final project report was "Design
Methods for Reducing the Risk of Progressive Collapse in Buildings," by
Edgar V. Leyendecker and Bruce R. Ellingwood.  The bibliography lists the
various project reports.   It was published in April 1977 as NBS Building
Science Series 98.  The report was an attempt to present various approaches
to handling what then was considered a controversial design issue.  One
analysis example of a masonry building (hand calculations) is included.

The report included two approaches that Bruce and I described as Direct
Design and Indirect Design.  Direct Design included either (1) alternative
load path (get in redundancy so other load paths will exist in the the
building if a critical member is lost) and (2) Specific Local Resistance.
The second procedure, which generated the most reaction, required designing
critical members to resist abnormal loads so such a member would not be
lost.  The report describes abnormal loads that might be considered in
design.  It includes the statistics of various abnormal loads.  Examples
include gas explosions, vehicular collision, airplane collisions, etc.  The
Indirect Design approach considered implicit consideration of improving
resistance to progressive failure by providing minimum levels of strength,
continuity, and ductility.  All of this was intended to result in what the
British code progressive collapse requirements called a "healthy and robust
structure."  I like the ring of that phrase.

A good portion of the ideas in ASCE 7-93 came out of the NBS project.  I
was a member of a small subcommitte on progressive collapse, headed by Bill
McGuire - who spent a sabbatical at NBS, that worked on the original effort
to have some guidance on progressive collapse design placed in the 1982
version of ANSI A.58 (which eventually became ASCE 7).

All of this was a long time ago and far different from what I do now.  It
is interesting to see it discussed.

E.V. Leyendecker, USGS

  At 08:12 AM 8/10/1999 -0700, you wrote:
>If you're interested in a good (but dated) summary of how the subject is
>treated in building codes (mostly European), check out "The Avoidance of
>Progressive Collapse - Regulatory Approaches to the Problem" by National
>Bureau of Standards, NBS-GCR 75-48.  My copy is dated October 1975 but maybe
>somebody out there knows of a newer version...
>Brian McDonald
>-----Original Message-----
>From: James Lane, P.E. [mailto:jamesalane(--nospam--at)]
>Sent: Monday, August 09, 1999 11:11 AM
>To: seaint(--nospam--at)
>Subject: Progressive Collapse Design
>I have an upcoming project requiring design for progressive collapse. What 
>are the sources for such design, manuals, FM's, books, etc? Has anyone used 
>RAM Xlinea for such design?
>I believe if you have not been required to design with this in mind you will
>in the near future.
>Get Free Email and Do More On The Web. Visit
Edgar V. Leyendecker                   Telephone:  303-273-8565
U.S. Geological Survey                 Fax:        303-273-8600

email: leyendecker(--nospam--at)
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