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RE: IBC 2007 Wind calcs.

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I just put it in my spreadsheet after reading some of the posts on this
thread.  The code is supposed to be a cook book not a puzzle.

-----Original Message-----
From: chris.slater(--nospam--at)gmail.com [mailto:chris.slater(--nospam--at)gmail.com] On Behalf Of
Chris Slater
Sent: Thursday, February 14, 2008 3:40 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: IBC 2007 Wind calcs.

Right.  I account for that by calculating a 10 psf load (that's the W1-10,
W2-10, etc) and if that's greater than what I come up with by the other
method, I use it.


On Thu, Feb 14, 2008 at 4:03 PM, Haan, Scott M POA
<Scott.M.Haan(--nospam--at)usace.army.mil> wrote:
> If you read the guide - I think per ASCE 7-05 6.1.4.1 you are supposed 
> to use  a minimum of 10 psf projected on the vertical surface when you 
> have no  horizontal pressure component on the roof.  I rest my case: 
> not as easy as  the UBC.
>
>
>
>  -----Original Message-----
>  From: chris.slater(--nospam--at)gmail.com [mailto:chris.slater(--nospam--at)gmail.com] On 
> Behalf Of  Chris Slater
>  Sent: Thursday, February 14, 2008 2:46 PM
>  To: seaint(--nospam--at)seaint.org
>  Subject: Re: IBC 2007 Wind calcs.
>
>  All of this talk is making me worry that we're doing something 
> horribly  wrong...
>
>  I put up a sample of the way we're doing our wind calcs here:
>  http://www.examplecalcs.com/hosted/18329.pdf
>
>  I use a program to generate the A, B, C and D loads.   If the B and D
>  loads are negative, I just use 0.  Then I generate my wind loads by 
> taking  the B pressure from the ridge down to the plate, and the A
>  pressure from the plate to the middle of the wall height.   In the
>  example I posted, W1 and W2 are calculated that way.
>
>  For gable ends, or lower levels, I just use the A load from the top 
> of the  projected area to the middle of the lower wall, which is how I 
> got
>  W3 and W4 in the example.
>
>  For long buildings, I will sometimes use the C and D loads for the 
> section of  the building that is more than 2a from the corners, but in 
> general, I just  use the A and B loads since these tend to be lower 
> than the projected area  winds we used in the old UBC code.
>
>  It's not simple, but it's not incredibly complicated either.  Which 
> makes me  worried.  Am I missing something, or does this seem like a 
> reasonable  approach.
>
>  Chris
>
>  On Thu, Feb 14, 2008 at 2:58 PM, Haan, Scott M POA  
> <Scott.M.Haan(--nospam--at)usace.army.mil> wrote:
>  > Scott.
>  >
>  >  Compared to the UBC, all the ASCE 7 methods are more complicated.  
> I  > agree  with people who said use the analytical method for a rigid  
> > building is the  easiest way because there aren't 10 different zones  
> > etc... etc... but you  still have to have a spreadsheet to calculate 
> the  pressures.
>  >
>  >  I think if I had to design a flexible building I would send 
> chocolate  > cupcakes with turds in the middle to the ASCE7 wind 
> committee have a  > supercomputer to calculate the gust factor.
>  >
>  >  Scott.
>  >
>  >
>  >  -----Original Message-----
>  >  From: Scott Maxwell [mailto:smaxwell(--nospam--at)umich.edu]  >  Sent: 
> Thursday, February 14, 2008 9:58 AM  >  To: seaint(--nospam--at)seaint.org  >  >  > 
> Subject: RE: IBC 2007 Wind calcs.
>  >
>  >  I want to say that this method is more or less based off the  > 
> simplified  method that Washington has produce and has been mentioned 
> by  others.
>  >
>  >  Personally, while I find there to be some complexities that I 
> don't  > feel are  necessarily needed in the current ASCE 7 wind 
> provisions, I  > don't find them  that difficult to use...including 
> Method 1.  I find  > that I can pump out wind  pressures in method 1 in
very short order.
>  > It does take more time to use  those pressures to analyze stuff in  
> > MWFRS since they now have corner  pressures and such...but you don't  
> > really gain that much compared to older  more "uniform" pressures  > 
> except for some buildings that might be rather  succeptible to  > 
> torsional effects.  But it does help that I have been using  the ASCE  
> > 7 methods for a LONG time, while engineers in CA are more used to  
> only  using the simplified methods that were in the UBC.
>  >
>  >  I would be the first to agree that ASCE 7 has gone of the deep end 
> to  > some  degree in "sharpening the pencil" for wind provisions, but 
> I am  > not sure that  I would liken them to a doctoral thesis (unless 
> you are  > talking about the  wind provisions for signs or flexible 
> structures or  > dynamically sensitive  structures and have to start 
> calculating gust  coefficients).
>  >
>  >  Regards,
>  >
>  >  Scott
>  >  Adrian, MI
>  >
>  >         -----Original Message-----
>  >         From: Matthew [mailto:sandman21(--nospam--at)gmail.com]
>  >         Sent: Thursday, February 14, 2008 12:48 PM
>  >         To: seaint(--nospam--at)seaint.org
>  >         Subject: Re: IBC 2007 Wind calcs.
>  >
>  >
>  >         You can also try using
>  >
>  > 
> http://www.documents.dgs.ca.gov/dsa/pubs/IR-16-7_WindLoad_12-18-07.pdf
>  >
>  >         Matthew
>  >
>  >
>  >         On Thu, Feb 14, 2008 at 9:34 AM, Paul Feather
>  > <PFeather(--nospam--at)se-solutions.net> wrote:
>  >
>  >
>  >                 Stan,
>  >
>  >                 First off, the simplified method is anything but
>  > simple.  We  use the
>  >                 general method (method 2) for everything and get more
>  > consistent results
>  >                 easier.  The simplified method is derived from metal
>  building
>  >                 manufacturer methods, and for anything but a metal
>  > building  results in a
>  >                 complete book keeping atrocity.
>  >
>  >                 You are looking at 25 degrees area B.  The way the
>  > simplified  method
>  >                 works this is just one small area that cannot be
>  > applied in  the same
>  >                 thinking as the UBC horizontal projected area.  You
>  > have to  add the area
>  >                 B to the Area E uplift, basically all areas A through
>  > H get  applied
>  >                 simultaneously as one load case.  Then you rotate the
>  > building reference
>  >                 corner and apply the whole thing again for all four
>  > reference  corners.
>  >
>  >                 Get away from the simplified methods and you will
>  > simplify  your life,
>  >                 while getting something closer to what you are used
>  > to.  I  don't believe
>  >                 the ASCE wind provisions could be any more convoluted
>  > and  difficult to
>  >                 apply to real world engineering if we tried.  The UBC
>  > methods  were
>  >                 derived as a conservative simplification of the ASCE
>  > provisions years
>  >                 ago, and we desperately need to achieve something
>  > similar  again.
>  >                 Spending three days on a doctoral thesis to develop
>  > simple  wind
>  >                 pressures as opposed to working on load path and
>  > quality  engineering is
>  >                 counter-productive, and saving 1.4 psf in wind
>  > pressure only  matters to
>  >                 mass produced square boxes trying to be paper thin.
>  >
>  >                 Paul Feather PE, SE
>  >                 pfeather(--nospam--at)SE-Solutions.net
>  >                 www.SE-Solutions.net <http://www.se-solutions.net/>
>  >
>  >
>  >
>  >                 -----Original Message-----
>  >                 From: sscholl2(--nospam--at)juno.com [mailto:sscholl2(--nospam--at)juno.com]
>  >
>  >                 Sent: Thursday, February 14, 2008 9:09 AM
>  >                 To: seaint(--nospam--at)seaint.org
>  >                 Subject: IBC 2007 Wind calcs.
>  >
>  >
>  >                 After 40 yrs. of doing UBC calcs. I am attempting to
>  > do my  first IBC
>  >                 calcs. and need help, even after attending a seminar,
>  > which  seemed to
>  >                 cover lots of things but not this.
>  >
>  >                 For a simple house, using 6.4 Method 1 Simplified
>  > Procedure,  I cannot
>  >                 get a reasonable wind pressure of something between 15
>  > psf  and 25 psf.
>  >
>  >                 From 6.4.2.1 <http://6.4.2.1/> , I get p s= 1.0 (1.0)
>  > 1.0
>  >
>  > (2.3) = 2.3 psf which is
>  >                 unrealistic. This is using Fig. 6-2, exposure B, h=30
>  > ft.,  Kzt =1
>  >                 and I=1
>  >
>  >                 Can someone point out my omissions/errors?
>  >
>  >                 Stan Scholl, P.E.
>  >                 Laguna Beach, CA
>  >
>  _____________________________________________________________
>  >                 Click for a credit repair consultation, raise your
>  > FICO  score.
>  >
>  >
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>  >
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