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RE: ASCE 7-05

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Doug, Drew & Haan,
Thanks all for your comments.
Freeman

-----Original Message-----
From: Doug Mayer [mailto:doug.mayer(--nospam--at)taylorteter.com] 
Sent: Tuesday, October 23, 2007 12:41 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

Actually, in the 2001 CBC the combination of horizontal and uplift loads
is addressed, albeit vaguely.  First of all, if you are doing Method 1
per section 1621.2 it specifically says that "...the wind pressures
shall be assumed to act simultaneously normal to all exterior surfaces."
Therefore, the combination of horizontal and uplift loads is explicit
for Method 1.

Method 2 does not specifically address this combination.  However, in
the second paragraph of section 1621.1, the code states "...the
combination of the effects of uplift and overturning may be reduced by
one third" when dealing with a structure of a certain aspect ratio.
This implies that uplift and overturning (horizontal forces) are always
combined, regardless of method used.  

That is the way I have always read the wind provisions, but I'm not
positive it is correct.  Also, I can't say I have always considered
uplift when checking my overturning.  Hope that helps.

Doug Mayer, SE
Structural Engineer
 
TaylorTeter
Partnership
 
7535 North Palm Ave., Suite 201
Fresno, CA 93711
 
(559) 437-0887 Ph.
(559) 438-7554 Fax
doug.mayer(--nospam--at)taylorteter.com
 
 
-----Original Message-----
From: Freeman Tang [mailto:FTang(--nospam--at)gouvisgroup.com] 
Sent: Tuesday, October 23, 2007 12:20 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

I have a question regarding the standard practice especially in
California of considering the uplift and horizontal loads simultaneously
for wood-framed construction. First of all in the previous UBC codes
(say from UBC 1982 to UBC 1977/CBC 2001) considering the uplift and
horizontal wind loads acting simultaneously on a building was not
explicitly addressed and not mandatory required. Even though text books
and references have been indicating that these loads are acting
simultaneously but it seems to me that in our practice we just consider
them separately.  We use the horizontal wind load to design our lateral
force resisting systems and the uplift wind load is basically a
detailing issue by anchoring roof framing to the top level of the
building.  We never have any uplift problems for the buildings that we
designed and also we never have any questions from any building
departments.  In the ASCE 7-05 both the Simplified Method and Analytical
Method require, explicitly with diaphragms, that these two loads are to
be considered simultaneously.  Will there still be a difference between
standard practice and code requirements for wood-framed construction?
Anyone can give me some insight and comments on this issue?
Thanks.

-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan(--nospam--at)poa02.usace.army.mil] 
Sent: Tuesday, October 23, 2007 11:13 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

Bill:

The ASCE wind could have been written much simpler. Next to a hill
multiply
by 1.2, too narrow multiply by 1.1, too much glass multiply by
1.156162457724, a couple of tables, a map, a crayon, a calculator and
napkin
bing bang boom.

I drink the koolaid like everyone else but it doesn't mean I have to
like the
taste.


Scott.

-----Original Message-----
From: Scott, William N [mailto:William.N.Scott(--nospam--at)conocophillips.com] 
Sent: Tuesday, October 23, 2007 9:48 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

Given the wind damage that has occurred do to hurricanes, it seems the
wind
provisions were inadequate.

So, calculate a standard wind load for your area and use it for every
project
that has similar parameters. Leave the project info blank so it can be
written in.
 
Bill
-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan(--nospam--at)poa02.usace.army.mil]
Sent: Tuesday, October 23, 2007 9:40 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

This may rub academics wrong, but building codes should be written to
the
lowest common denominator. This is so mistakes won't be made, not so
that
idiots like me can do the work.  You shouldn't have to buy software or
spend
40 hours writing a spreadsheet to calculate wind loads in order to
figure out
what the code requires.  You should be able to easily open a code book
and
quickly hand check your computer model output with a calculator on the
back
of a napkin.  If not the code is broken.

I used to tell people to quit whining about code changes.  I haven't
been in
the profession that long though and have seen 3 different seismic
loading
codes and two wind loading codes.  I used to say no big deal to ASCE7
wind
but if history truly repeats itself then in the near future the wind
code
will be completely changed again. 

The UBC wind loads were much easier to apply.  The designs were not less
safe
otherwise everyone would be retrofitting buildings designed with UBC
wind
loads. 





-----Original Message-----
From: Brian K. Smith [mailto:smithegr(--nospam--at)bellsouth.net]
Sent: Tuesday, October 23, 2007 7:46 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

Charles,

	When was the last time a building failed in Texas, Mississippi,
or
Louisiana due to an earthquake?  I don't remember reading about that
event
either but the IBC says we have to consider it.  Not only that but in
many
cases I am required to detail the building to meet the seismic
requirements.

	I have been using the wind load provisions of the IBC and ASCE 7
for
7 or 8 years.  It's not that big of a deal.

Bks







-----Original Message-----
From: Charles R. Ashley Jr. [mailto:charles(--nospam--at)advanceeng.net]
Sent: Tuesday, October 23, 2007 10:15 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

As engineers we tend to learn by failures.  After all, it was the 1994
Northridge EQ that spurred major revisions to the seismic provisions in
the
1997.

So I have to ask....when is the last time a Type V building failed due
to
wind in California?  Anyone wake up in the morning and find a roof that
doesn't below to you sitting in your front yard?

I am trying to figure out what tragic wind event triggered these
ridiculous
revisions!  I am sure there must have been a bus load of innocent
children
involved, I just can't seem to find it.



-----Original Message-----
From: smaxwell(--nospam--at)umich.edu [mailto:smaxwell(--nospam--at)umich.edu]
Sent: Monday, October 22, 2007 3:35 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASCE 7-05

While I do believe that there are a lot of engineers out there who are
overly
harsh on the various code/standard committees (it is rather easy to
"backseat" drive or complain about stuff when you are not familiar with
the
process or the work that goes on and the difficulty in getting sometimes
50+
people to agree enough on something to produce a provision), I do
believe
that ASCE 7 has gotten a little out of hand with the wind provisions.
Having
messed with the wind loads for signs recently, I can say that it is WAY
to
involved a process to get wind loads for a freakin' sign (it took me
multiple
hours to JUST get the wind pressure for the sign).

Regards,

Scott
Adrian, MI

Quoting "Garner, Robert" <rgarner(--nospam--at)moffattnichol.com>:

>
> ASCE has very successfully made wind design into rocket science.  Way
to
> go ASCE!
>
> -----Original Message-----
> From: Gary L. Hodgson and Assoc. [mailto:ghodgson(--nospam--at)bellnet.ca]
> Sent: Monday, October 22, 2007 4:59 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: ASCE 7-05
>
> I will take back part of what I said.  The quality of engineering 
> drawings, particularly structural drawings from the US, are very good.
> However when you read computer instructions, technical manuals, and 
> codes where they have been prepared by engineering organizations, they

> usually leave something to be desired.  The trouble is that they know 
> all about  their subject but don't realize outsiders are starting from

> scratch; they just assume everyone will know what they mean..  An 
> example is 1995 ASCE-I bought their Minimum Design Loads for Buildings
> -- and after reading the seismic requirements three times I was
totally
> lost and thought the problem was me.  So I called a friend at a large 
> engineering company who was assistant head of the industrial
department
> and he said the ASCE seismic parts seem to go in circles.  We agreed
to
> ignore it and use the UBC, I believe.  I wrote a letter of complaint
to
> ASCE and heard nothing back.  If I am not mistaken, there have been a 
> lot of complaints recently about the ASCE wind load requirements.
>
> Christopher Wright wrote:
>>
>> On Oct 20, 2007, at 8:21 AM, Gary L. Hodgson and Assoc. wrote:
>>
>>> Actually makes sense, as engineers are not known for their 
>>> communication ability Gary
>> Not the good ones. Engineering is discipline of communications--we 
>> don't (routinely) make things; we tell people who do how to makes 
>> things properly. That's what drawings and reports are all 
>> about--communicating instructions unambiguously to artisans (for lack

>> of a better word) can give materials a specific usefulness. We don't 
>> do science or math; we use science and math to make sure the 
>> instructions we communicate are soundly based in physical principles.
>>
>> My own experience is that academics who teach engineering tend to
lose
>
>> sight of the need for communications and organization--maybe out of 
>> desire for greater rigor in presentation or just a tendency to
impress
>
>> the onlooker with technicalities. I know that's happened with the 
>> Pressure Vessel Codes. With the ASME Codes, I think the problem is 
>> that industry isn't supporting Code writng efforts like they once
did,
>
>> and academia has necessarily moved in. I've always suspected (without

>> an ounce of actual proof) that it's what happened when LRFD was 
>> introduced.
>>
>>
>> Christopher Wright P.E. |"They couldn't hit an elephant at
>> chrisw(--nospam--at)skypoint.com   | this distance" (last words of Gen.
>> .......................................| John Sedgwick, Spotsylvania
>> 1864)
>> http://www.skypoint.com/~chrisw/
>>
>>
>>
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