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RE: ASCE 7-05 Cantilevered Columns?
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: ASCE 7-05 Cantilevered Columns?
- From: "Acharya, Suresh" <Suresh.Acharya(--nospam--at)ci.concord.ca.us>
- Date: Mon, 25 Feb 2008 13:10:27 -0800
Per Section 11.2, Inverted Pendulum-Type Structures are defined as
structures in which more than 50% of mass is concentrate at top
of a slender cantilevered structure and in which stability of the mass
at the top of the structure relies on rotational restraint to the top
of the cantilevered element.
Suresh Acharya, S.E.
Good point, but still not sure what would be
used- An R of "3" for "distributed mass cantilevered structures", or an R of
"2" for "invreted pendulum" structures. Averaging these out comes up with an R
of "2.5", which, again, seems reasonable to me, (back to an R of "2.2" for the
'97 UBC/'01 CBC).
Larry Hauer S.E.
Subject: RE: ASCE 7-05 Cantilevered Columns
Date: Mon, 25 Feb 2008
I suggest looking at Table 15.4-2 for "nonbuilding structures
not similar to buildings" - but it still requires some interpretation.
CH2M HILL /
I don't think Sec. 188.8.131.52 or .7 is
applicable since those would be OMF's with steel beams and moment
connections. What I am talking about are "flag pole" structural elements
such as cantilevered WF columns out of a grade beam or cantilevered pile
foundations. Unless someone can convince me other wise I will be designing
them with an "R" of 2.5 per Table 12.2-1 Item "G.1", (Special Steel Moment
Frames". My rational is that the columns don't know whether they are
"Special" or "Ordinary", (Item "G.3"), since there is no moment connection
at the top, and an R of 2.5 equates to approximately an R of 2.2 which was
required in the '97 UBC. I feel an R of 1.25 is way to
Any opinions would be
Thanks in advance,
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