huangyhg

sway comfort level
anyone know of a survey of "comfortable" or "discernible" building sway due to wind loading (not seismic drift limitations)? i assume this will be noted as a max lateral deflection as a percentage of the building height (ie. h/1000) or preferably, for this application, by an acceleration limit (ie. 0.05g). thanks-
my old structural professor was dale c. perry who now teaches the wind load seminars for asce. he use to tell stories of interviewing people in high rises in chicago and new york. some peoples favorite pass time was going in the bathrooms when the wind was blowing and watching the white caps on the toilets. he is now an architectural structures professor at texas a&m and would be a good contact. he can also be contacted through the asce continuing education office.
keep in mind the human factor! what makes one person sick (or motion sick) is perfectly fine with others. i heard of people living/working in swaying building and they were fine till they heard someone complaining. then their minds went to work?
do not forge that vibrations also come to play. dr. tom murray at virginia tech wrote aisc design guide number 11 which deals with the vibrations and human comfort thresholds. dr murray also wrote software that deals with the study of vibrations. sji also published a booklet and software that deals with the same subject.
it is my opinion that it is all relative to the person. the general guide lines to limit lateral drift for structures seem to work well since most of the existing buildings are designed to these limitations.
i would add that some of murray's work includes the modified reiher-meister graph which charts the displacement amplitude against the frequency of vibration. the graph is divided up into four areas of human response:
strongly perceptible
distinctly perceptible
slightly perceptible
not perceptible
here's a pdf file on the web that shows it.
there is a deflection index guide in the structural engineering handbook by gaylord & gaylord. it is based on criteria developed by the new york firm of weiskopf & pickworth and can be found in the chapter on tall buildings.
the canadian building code used to limit inter-story drift to h/500, or h/400 if the building finishes are detailed to accommodate the calculated drift. i have not practiced there since 1990, so cannot say whether that requirement has changed. it is probably a good guide for office buildings and similar structures up to about 40 stories. if you have an unusual wind condition or a more slender structure, then a more detailed analysis would be appropriate.
nigel

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