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RE: Wind Loads on Monopoles[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: Wind Loads on Monopoles
- From: "Horning, Dick/CVO" <dhorning(--nospam--at)CH2M.com>
- Date: Tue, 1 Sep 1998 10:58:02 -0600
At this point maybe you're better off to bite the bullet than continue wrangling with the Bldg Official (disallowing the 2/3 factor for a cylindrical pole seems unreasonable, though, basic aerodynamics would indicate a lower drag coefficient for a circular section). If, on the other hand, you want to pursue it further with him, a good resource would be John Loscheider, SEAW member and a key player in their Wind Commentaries on the UBC . I don't have a number for him, but he's probably in the Seattle yellow pages under Loscheider Engineering Co. > ---------- > From: Bill Allen, S.E.[SMTP:bill(--nospam--at)allendesigns.com] > Sent: Tuesday, September 01, 1998 9:33 AM > To: seaint(--nospam--at)seaint.org > Subject: RE: Wind Loads on Monopoles > > I have applied a Cq=1.4 to the attachments. > > The building official won't buy Cq=0.8 for the pole (not even > Cq=0.93=1.4*2/3). > > The 25 psf requirement essentially negates any application of Ce, Cq, etc. > as well as any reduction for low elevation. > > Regards, > Bill Allen > > -----Original Message----- > From: Horning, Dick/CVO [mailto:dhorning(--nospam--at)CH2M.com] > Sent: Tuesday, September 01, 1998 9:13 AM > To: 'seaint(--nospam--at)seaint.org' > Subject: RE: Wind Loads on Monopoles > > > Here's a possibility - > You're using a wind speed of 70 mph. A number of special-purpose codes > (such as AWWA D100 for steel reservoirs) assume 100 mph wind speed. Using > a > stagnation pressure of 25.6 psf, it wouldn't require more than a 15' pole > in > Exposure C to get up to 25 psf. > Having suggested that, if the pole is essentially clean of attachments or > projecting elements, I would use Cq = 0.8 as you did. > > > ---------- > > From: Bill Allen, S.E.[SMTP:bill(--nospam--at)allendesigns.com] > > Sent: Monday, August 31, 1998 4:18 PM > > To: seaint(--nospam--at)seaint.org > > Subject: Wind Loads on Monopoles > > > > I have received some plan check comments on a foundation design I have > > prepared. This foundation supports a monopole, 30 inches in diameter and > > 100 > > ft. tall. The foundation is 5 ft. diameter and 15 feet deep. I used the > > UBC > > flagpole formula for the design (non-constrained). > > > > For the design, I used a Cq of 0.8 for the pole (based on "Chimneys, > tanks > > and solid towers" in UBC table 16-H). The plan checker wants me to > > consider > > the monopole as "Signs, flagpoles, lightpoles and minor structures" and > a > > Cq > > of 1.4 with a 2/3 reduction for cylindrical elements. The kicker is > (this > > is > > a DSA project) that, in the CA UBC, there is an additional footnote to > the > > table which reads "Minimum wind design pressure for flagpoles and > > lightpoles > > shall be 25 pounds per square foot." This equates to a wind pressure for > a > > structure 350 feet tall w/o reductions (Ce=2.12, Cq=2/3*1.4, qs=12.6). > > This > > footnote does not appear in the regular version of the UBC. > > > > I am interested if anyone has a reference for this code requirement and > > what > > kind of structure the authors of this provision was this provision > > intended. > > > > Regards, > > Bill Allen > > > > > > > >
- RE: Wind Loads on Monopoles
- From: Bill Allen, S.E.
- RE: Wind Loads on Monopoles
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