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RE: Tales of Terror #1: Architects doing engineering

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Chuck,
There are a couple of issues here and yes, I might agree with you to a
limit:
1. First, the designer is to use a rational method of lateral distribution.
In this case, the diaphragm is treated like a series of simply supported
beams. So, the distribution of shear should represent the statics of a
uniformly loaded series of beams. In my case (the project presented) the
diaphragm load was large due to the span and the depth of the diaphragm and
the reaction at the middle wall was significant. If we are to accept
anything, then we (designers) should stick with the principles of mechanics
and plan checkers need not deviate from this without supporting and accepted
practices.

2. I don't recall the test you were referring to, but there was a
publication in the SEAOC Proceedings (following the annual convention)
involving the test of a simple building where the continuous blocking at the
double plate was omitted and the engineer's publication was intended to
point out that the shear transfer occurs without the blocking. This was the
Ficcadente study that was MISTAKENLY published in the SEAOC Proceedings
without prior review. The tests were performed to justify the claims of the
contractors expert witness; Mr. Ficcadente.  Furthermore, the tests may have
been submitted to the governing city with the intent of having the building
official accept the testing for the project. SEAOC subsequently issued a
disclaimer indicating that they were no approving or associating themselves
with Mr. Ficcadente's claims. Certainly, the testing could not be used to
substantiate his claim on all light-framing projects. 

Look, you might be right in your claim of how loads are distributed -
certainly you exceeded the minimum principles of mechanics (statics) by
distributing forces 1/3, 1/2, 1/3 - the end walls were given a higher
demand, but you can not, by the nature of the code, present a distribution
that is less than the minimum requirements established in the rational
methods - in this case the basics principles of mechanics.

Regards,
Dennis

 


Dennis S. Wish, PE


California Professional Engineer

Structural Engineering Consultant

dennis.wish(--nospam--at)verizon.net

http://www.structuralist.net

 


-----Original Message-----
From: chuck utzman [mailto:chuckuc(--nospam--at)pacbell.net] 
Sent: Tuesday, June 29, 2004 9:45 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Tales of Terror #1: Architects doing engineering

Dennis-
IMHO the dumb architect has it right  & you persist in doing  it wrong :o)
Every test I'm aware of shows the distribution to be 1/3, 1/3, 1/3. (If  
it doesn't  change the wall construction, I sometimes use 1/3, 1/2, 1/3 
just to keep plan checkers like you at bay.)

At a SEOC convention in S.F. a few years back, researchers from Texas 
IIRC presented their test results from a simple unblocked pitched roof 
building.  The uniform load at the top plate distributed itself  1/3, 
1/2, 1/3.  Likewise for every reasonably proportioned floor platform.

Chuck Utzman, P.E.

Dennis Wish wrote:

> I started to write this in order to vent my frustration as a contract 
> (sub-contract) plan checker who has found that more architects are 
> designing the structural elements of high-end custom homes. This is 
> upsetting – I’m actually making money as the more errors I find, the 
> more time I spend and the more I make hourly. I don’t need to design 
> their homes, I only need to plan check them.
>
> Don’t misunderstand, I know a great many architects who became 
> engineers and they went through the hard work to prove they were 
> capable. But what I am seeing are architects who think they remember 
> their statics and strength of materials from forty years ago and 
> attempt to apply it today in order to save the cost of hiring an 
> engineer. Three or four plan check cycles later, they tend to find 
> engineers to help them through the things they don’t understand.
>
> Just one example – I can’t resist this one. The designer (I am 
> hesitant to use the title architect) calculates the base shear of a 
> fairly rectangular building with three lines of resistance. Rather 
> than waste the time to design the distribution of the two diaphragms 
> between the three grid lines as simply supported beams, the architect 
> applies 1/3 of the total lateral load to each line of shear. Have I 
> missed something? I’ve been used to figuring the reactions which 
> almost always ends up with 50% of the shear in the middle wall and 25% 
> at each end. He would have been better off eliminating the center 
> shearwall had it not been for a re-entrant corner and don’t get me 
> started on that one.
>
>  
>
> What has this world come to when BORPELS (California) has no control 
> over architects practicing engineering and the office of the 
> Department of Consumer Affairs that licenses Architects will do 
> nothing until the damage occurs and the Architect is considered 
> potentially negligent (I’ve checked – trust me).
>
>  
>
> Politics has reached every segment of our society – I mention 
> certification of Framers and find the BIA (Building Industry 
> Association) putting me on their black list.
>
>  
>
> So, what’s your take on all of this? Should I just retire to 
> Southeastern Arizona and become a hermit (with my wife family and dogs)?
>
>  
>
> Dennis
>
>  
>
>
>       Dennis S. Wish, PE
>
> California Professional Engineer
>
> Structural Engineering Consultant
>
> dennis.wish(--nospam--at)verizon.net <mailto:dennis.wish(--nospam--at)verizon.net>
>
> http://www.structuralist.net <http://www.structuralist.net/>
>
>  
>
>
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