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FEMA 273, Overturning and a possible solution to the problem.[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: FEMA 273, Overturning and a possible solution to the problem.
- From: FEMCCLURE(--nospam--at)aol.com
- Date: Thu, 11 Nov 1999 05:25:29 EST
- Cc: FEMCCLURE(--nospam--at)aol.com
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.
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