Need a book? Engineering books recommendations...
[SEAOC] Re: [SEAOC] Looking for newly designed SMRF buildings[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaoc(--nospam--at)power.net
- Subject: [SEAOC] Re: [SEAOC] Looking for newly designed SMRF buildings
- From: Julie Mark Cohen <jmcohen(--nospam--at)emf.net>
- Date: Sun, 16 Jun 1996 14:40:06 -0700 (PDT)
Dear Abdelkater, For your information, I have a PhD from structural engineering at Cornell (1987). I have over 12 years of experience in practice and self-initiated research for which I have procured my own funding. If you want drawings from SEs, it is likely that the SE will have to get written permission from building owners to have _someone else_ analyze their buildings, even if you tell them that you won't use the building names and locations. Most building owners do NOT give permission for this. I know of several profs who have been sued for doing just this, mostly because they found weaknesses or deficiencies in the SEs work -- which made the building owner upset with both the SEs and researchers. You don't need this aggravation! Out here, you can be sued for what you have and for _future_ earnings. Don't try to "design" buildings on your own, unless you have experience as a lead engineer in an office. Likely, you will come up with something that might be code-compliant, but not usable in practice, especially if you are unfamiliar with the architecture of various classes of buildings. (Structural framing should be indicative of architectural function!) Try to get building drawings from SMIP, USGS, etc. At least you could calibrate your analytical model to elastic response of these buildings. Analyzing real buildings without the benefit of recorded data from actual ground shaking or without actual failures leads to results that are questionable. (You may have to plan some trips to SMIP, USGS, etc., because they don't mail drawings out. You can go to the various offices, looking through what they have, and make copies (which you have to pay for).) It may be possible to get limited drawings from city building officials, but this path is not as direct as others. You need both structural AND architectural drawings to do a proper job. Structural drawings alone are *not* enough. They are necessary but not sufficient. I have lists of lists of real buildings in which the arch'l drawings were ignored and in which the analytical models were a total waste of time -- they predicted the behavior of unrealistic buildings!! Also, please be VERY careful about what you are doing -- the majority of buildings built in California since the early/mid-1990s have had their structural framing minimized, not optimized. Since there are no code requirements about 3-D structural framing systems, these buildings are not particulary good, in general. (Check out my Dec. 1994 ASCE CE magazine Forum article entitled "The Northridge Warning: Has 3-D Design Been Lost.") It is highly likely that these buildings will suffer from failure modes that you will not "see" in your analyses (yes -- I have used several nonlinear time-history programs and NONE of them, to date, have analytical models that can capture what is anticipated by me and our senior colleagues). Also, note that there is still a huge gap between performance criteria of structural framing and alleged nonstructural elements/component/systems. If you handle this problem correctly and fill in what's missing in the documents you sited below, you will break the record for time for your PhD in structural engineering, which, I believe, was set by one of my classmates at 10 years. You should plan things out to do something with a comprehensive basis, but not a life's pursuit. To be of any benefit to practitioners, you need, at the very minimum, to note in detail what is missing in the documents you mentioned. My list from these is very long and highly detailed, but I have only been working on it for a very few hours. How much information do you have on the influence of, say, heavy cladding on steel framed buildings? The state-of-practice leads to an analytical model that is grossly UNconservative (see "Seismic Performance of Cladding: Responsbility Revisited, by JM Cohen, ASCE's J. Performance of Constructed Facilities). Did you know that in some buildings that the mass of cladding panels is almost 20% of the superstructure? It is INcorrect to assume that these panels _only_ "conservatively" increase the periods of vibration of the framing -- most modern steel-framed buildings exhibit significant higher mode response -- again, please see my paper. In the past 6-7 years, I have reviewed quite a few analytical models, offering comments on whether or not they represent the building at hand and, if not, whether they represent another building that is realistic. *If* your documentation is clear, very clear, including how your assumptions are implemented into input for the various computer programs, I might be able to offer a little bit of time on this. Good luck! Julie Cohen (Cornell structural engineering PhD, 1987) ------------------------------------ | Dr. Julie Mark Cohen, P.E., | | Director and Principal | | Cladding Research Institute | | 6 Commodore Drive, Suite 330 | | Emeryville, CA 94608-1620 | | Tel (510) 654-7917 | | FAX (510) 4500-CRI | ------------------------------------ On Sun, 16 Jun 1996, Abdelkader K. Tayebi wrote: > Dear Fellow Structural Engineers, > > I am a PhD student at Cornell University doing research in the area of > performance based design in the line of ATC-33 (FEMA 272/273) and > Vision 2000 projects. As part of my research I am evaluating various > nonlinear and pseudo nonlinear methods that can be recommended for future > seismic codes. For the parametric studies I am using a number of hypothetical > regular Special Moment resisting frame buildings I designed according to > UBC94 for California Environment. > > To make this research more worthy and of practical impact, I want to > analyse actual buildings that have been built recently according to the > latest codes (UBC91 or 94) . As all of you are in design > firms, I am asking those of you who can, to provide me with buildings you know of > that fit what I am looking for. I will share with you all the results I > would obtain from the research undertaken on these buildings and I will > provide you with all the details of the types of analyses I would perform on these > buildings before hand. > > I really appreciate your cooperation and you invaluable help. > > Please reply to kamel(--nospam--at)maggie.cee.cornell.edu > > Sincerely, > > Abdelkader Kamel Tayebi Tel. 607-272-4976 > PhD candidate Fax. 607-255-9004 > Cornell University > School of Civil & Environmental Engineering > 220 Hollister Hall > Ithaca NY 14853 > > ... > > ...
- [SEAOC] Looking for newly designed SMRF buildings
- From: Abdelkader K. Tayebi
- [SEAOC] Looking for newly designed SMRF buildings
- Prev by Subject: [SEAOC] Re: [SEAOC] line
- Next by Subject: [SEAOC] Re: [SEAOC] LRFD Vs. ASD?
- Previous by thread: [SEAOC] Looking for newly designed SMRF buildings
- Next by thread: [SEAOC] It's not clear to whom responses are going, sorry.