Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

FEMA 273, Overturning and a possible solution to the problem.

[Subject Prev][Subject Next][Thread Prev][Thread Next]
For over two and one-half years I have attempted to explain to the authors of 
FEMA 273 (get their attention without much success) that there is a problem 
in how FEMA 273 attempts to address the overturning problem in FEMA 273, 
Section 2.11.4 Overturning, using Equation (2-15) and the "side-bar equation" 
on page 2-38.

Someone once told me (it was probably my mother), that if I was not part of 
the solution, I was probably part of the problem.  I admit to being part of 
the "problem" because I will not give up my continuing questioning of how 
FEMA 273 attempts to address the overturning problem.  I realize that the 
proposed ASCE/FEMA 273 and ASCE/FEMA 310 will address this problem 
eventually, but I have not had much encouragement reading the revisions to 
date on the ASCE/FEMA 273 and ASCE/FEMA 310 web site: 
http://www.degenkolb.com/ascefema273.html.

Now, I am offering a possible "solution" to the FEMA 273 Overturning problem, 
based on the help of a respected member of the earthquake engineering 
profession (someone you have probably all heard of or know), in a personal 
communication to me he has proposed the following solution, with which I 
completely agree:

    "It seems to me that the only way to address interface between structure 
and foundation is to have a separate section on foundations to address 
seismic issues (in ASCE/FEMA 273 and  ASCE/ FEMA 310 proposed standards, my 
added wording).  It needs to address the overturning question in a mature 
manner based on the dynamics of structures.  It needs to be a limit state 
approach how the forces are mobilized and resisted.  The relative effects of 
rigid base vs. rocking, how much uplift can be allowed, and the effects on 
the structure when uplift occurs."

Please do not ask me to provide the ASCE/FEMA 273 or ASCE/FEMA 310 wording to 
accomplish the goals in the above quoted paragraph on how the resolve the 
problems with the original FEMA 273 wording concerning "Overturning."

I sincerely believe that it is the professional responsibility of the authors 
of  the original FEMA 273 Guidelines to provide the required wording to lead 
us out of the FEMA 273 Overturning "wilderness" because they have lead us 
there.

By copy of this email message to the SEAOSC List Server and to these authors 
of FEMA 273 Guidelines and ASCE/FEMA 273 and ASCE/FEMA 310 proposed 
standards, I respectfully am asking them to reply to my "solution."  If other 
subscribers to the SEAOSC List Server would like to copy my email and send it 
to others and/or respond to my "solution", then please feel comfortable to do 
so. 

In closing, I cannot give you any assurance that I will stop asking the 
pertinent questions concerning how FEMA 273 attempts to address the 
"Overturning'  problem, except to patiently wait for what I consider a 
proper, mature rational engineering explanation of these unanswered questions 
concerning FEMA 273, Overturning.  I believe I owe it to the structural 
engineering and earthquake engineering professions and the public, as a 
professional obligation, to keep these  "Overturning" issues alive, until 
properly resolved, particularly now that I have proposed a "solution."

Thank you for talking the time to reading the above email message and I await 
your replies.



Frank E. McClure   FEMCCLURE(--nospam--at)aol.com   November 11, 1999.