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RE: IBC 2007 Wind calcs.

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I am not sure that codes are meant to be "cook books", even if that is what
they have become or perceived to have become.  Code are meant to be minimum
standards that are to be met, but it is still supposed to be the engineer
that uses engineernig judgement to determine if that is enough or if more in
needed.

I agree that it should not be a puzzle.  But, I don't find the wind
provisions to be that puzzling (there is lots of other stuff that is
puzzling at times).  If you want to continue your analogies, I consider
current wind provisions (except the felxible building stuff...those are a
puzzle at times...and I liked your chocolate cupcake with a turd idea) to be
a more extensive recipe in the cook book than the recipe that was in the
UBC...it is not any tougher to figure out, per se, but takes longer the
make/cook...which is due to the fact that the recipe is no longer just for
chocolate cupcakes (California), but also for vanilla, strawberry, and swirl
cupcakes (other locations with higher wind issues) (turd in middle
optional).

Regards,

Scott
Adrian, MI

-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan(--nospam--at)usace.army.mil] 
Sent: Thursday, February 14, 2008 7:59 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: IBC 2007 Wind calcs.


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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>  >
>  >
>  >
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