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Fw: Partially rigid connection design

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Perhaps we are not that far apart on this issue, as I agree with your
points below.  I think that it becomes a matter of opinion, however, when
defining the level at which an interest becomes "irresponsible".  If an
engineer has a boss who is accomodating, or chooses to explore his
interests on his own time, then IMO it is not irresponsible.  Furthermore,
if an engineer really doesn't have an interest in knowing why codes require
what they do, then fine, he can use the canned equations regardless of
whether he actually understands their intent or not (although I definitely
wouldn't want to work with such a person).  

MY point was that this thread was based on a question concerning
engineering design.  As I saw it, he was being chastised for being curious
and sharing his curiousity, and that was definitely inappropriate.  If I
feel that a particular thread is uninteresting or even useless, I just
don't read it.


T. Eric Gillham PE



___________________________________________
> 
> 		-----Original Message-----
> 		From:	Bill Allen, S.E. [SMTP:Bill(--nospam--at)AllenDesigns.com]
> 		Sent:	Thursday, June 25, 1998 9:18 AM
> 		To:	seaoc(--nospam--at)seaoc.org
> 		Subject:	RE: Partially rigid connection design
> 
> 		I am not saying that good research is not a worthwhile
> endeavor. What I am
> 		saying is that I believe there are three elements/phases
> of engineering:
> 
> 		1. The science of engineering-Testing, research,
> development of algorithms,
> 		etc.
> 		2. The art of engineering-Extrapolating the testing,
> research, etc. to "real
> 		world" problems
> 		3. The business of engineering-The act of performing the
> above within
> 		contractual budgets and schedules.
> 
> 		It would be irresponsible to be spending time on one
> element while being
> 		paid to do another. IMO, a lot of code documents appear
> that they were
> 		prepared ignoring the consequences of item 3.
> 
> 		Regards,
> 		Bill Allen
> 
> 		-----Original Message-----
> 		From: T. Eric Gillham [mailto:gk2(--nospam--at)kuentos.guam.net]
> 		Sent: Thursday, June 18, 1998 4:48 PM
> 		To: seaoc list
> 		Subject: Fw: Partially rigid connection design
> 
> 
> 
> 		I whole heartedly agree with Majid.  Those PhD issues
> form the bases for
> 		our real world solutions.  I feel that it is a healthy
> curiousity and
> 		desire know the underlying reasons for things that
> separates a technician
> 		from an engineer.
> 
> 		T. Eric Gillham PE
> 		----------
> 		> From: Majid Sarraf <msarraf(--nospam--at)uottawa.ca>
> 		> To: seaoc(--nospam--at)seaoc.org
> 		> Subject: Re: Partially rigid connection design
> 		> Date: Friday, June 19, 1998 1:10 AM
> 		>
> 		> >Probably doesn't matter at this point since you have
> probably busted
> 		> >your company's budget and consumed all of the design
> fee pondering an
> 		> >issue more suited for a PhD thesis than a "real
> world" design problem.
> 		> >Once your boss tallies the hours you have spent on
> this project, he
> 		> >probably will/should fire you.
> 		>
> 		> In my humble opinion,
> 		> Performance of steel connections is real world
> problem. I refer you to
> 		SAC
> 		> reports on performance of steel connections (modeled
> and designed for
> 		years
> 		> by engineers as unbeatable rigid connections!) during
> Northridge
> 		Earthquke.
> 		>
> 		> I do not deny that
> 		> some Ph.D thesis are far from practice, but many are
> not. In fact if it
> 		was
> 		> not because of many Ph.D and Master's thesis project
> conducted in the
> 		past,
> 		> there would be basically no sound and proven equations
> and provisions in
> 		> design codes
> 		> to be used by engineers now!
> 		>
> 		> Lets us help one another to find practical solutions
> to engineering
> 		> problems, not by ignoring them and not by blaming each
> other for wasting
> 		> time to find solutions. Timely and sound solutions are
> needed whether
> 		found
> 		> in design offices ,or in universities. I personally do
> appreciate design
> 		> engineers who try to understand and use the code,
> rather than applying
> 		the
> 		> code blindly to finish up a job fast. Sound design
> should never be
> 		> sacrificed for saving time.
> 		>
> 		>
> 		> To determine degree of rigidity of connections and
> analysis of simple 2-D
> 		frames
> 		> refer to the book By W.F. Chen on Stability of
> Semi-rigid Steel frames.
> 		It
> 		> comes with a program to determine the rigidity and
> another program to
> 		> analyze 2-D frames with semi-rigid joints.
> 		>
> 		>
> 		> Regards,
> 		>
> 		> Majid Sarraf
> 		>
> 		>
> 		>
> 		>
> 		>
> 		> >
> 		> >Regards,
> 		> >Bill Allen
> 		> >
> 		> >Y. Henry Huang wrote:
> 		> >
> 		> >> Very interesting.  How do I then, apply this
> concept to a "real
> 		> >> structure"?
> 		> >> How do I control the different degree of "connector
> strength"?  Or on
> 		> >> the
> 		> >> other hand, how do I know an existing connection is
> partially rigid to
> 		> >> what
> 		> >> degree?  Will I be required to test the connection
> system to verify
> 		> >> this
> 		> >> relative rigidity?
> 		> >>
> 		> >> Y. Henry Huang
> 		> >>
> 		> >> Public Information wrote:
> 		> >>
> 		> >> > > ----------
> 		> >> > > From:         Christopher
> Wright[SMTP:chrisw(--nospam--at)skypoint.com]
> 		> >> > > Reply To:     seaoc(--nospam--at)seaoc.org
> 		> >> > > Sent:         Friday, June 12, 1998 8:09 PM
> 		> >> > > To:   SEAOC Newsletter
> 		> >> > > Subject:      Partially rigid connection design
> 		> >> > >
> 		> >> > > Here's a follow-up on connection design
> incorporating partial
> 		> >> rigidity
> 		> >> > >
> 		> >> > > (Shouldn't be much trouble getting this
> approach incorporated in
> 		> >> the
> 		> >> > > building code. ;->) :
> 		> >> > >
> 		> >> > >
> <http://www.macsch.com/aerospace/Library/auc97/p01397.pdf>
> 		> >> > >
> 		> >> > > The paper shows some of the factors involved if
> you actually mean
> 		> >> to
> 		> >> > > include connection stiffness in FEA results.
> The fact that you can
> 		> >>
> 		> >> > > include a certain effect doesn't mean that you
> can do so
> 		> >> practicably,
> 		> >> > > so
> 		> >> > > as to model a real situation, with some overall
> benefit to the
> 		> >> > > project.
> 		> >> > >
> 		> >> > >
> 		> >> > >
> 		> >> > >
> 		> >> > The difference between the "traditional analysis"
> and partial-rigid
> 		> >> > analysis is on the connector. The traditional
> analysis assumes the
> 		> >> > connector has an infinite rigidity. In most real
> structures, the
> 		> >> > connectors are deformable. Partial-rigid analysis
> takes the
> 		> >> connector
> 		> >> > strength into considerations.
> 		> >> >
> 		> >> > I provide two sets of results, as below, that
> were extracted from
> 		> >> > partial-rigid analyses.
> 		> >> >
> 		> >> > **Set 1: Axial Force**
> 		> >> > Connector    Connector       Connector
> 		> >> > Strength      Force(#)          Stiffness(#/")
> 		> >> > (input)         (output)           (output)
> 		> >> >
> 		> >> >  100%        1929.636          infinity
> 		> >> >   99%         1929.601          3.303E8
> 		> >> >   95%         1929.369          6.298E7
> 		> >> >   80%         1928.388          1.329E7
> 		> >> >
> 		> >> > This example shows the connector force and
> connector stiffness vary
> 		> >> with
> 		> >> > the connector strength. In the traditional
> analysis, we use only the
> 		> >>
> 		> >> > connector force to design the connector (and
> ASSUMES the connector
> 		> >> has
> 		> >> > an infinite rigidity).
> 		> >> >
> 		> >> > The procedure of partial-rigid analysis requires
> the connector
> 		> >> strength
> 		> >> > as an input, and will output the corresponding
> connector stiffness
> 		> >> > (**connector stiffness is an output**). The
> design procedure
> 		> >> consists of
> 		> >> > two steps. The first step is similar to the
> traditional analysis to
> 		> >> > design a connector for the connector force only.
> Then, we have the
> 		> >> > connector dimension. And, we can determine the
> effective area (A),
> 		> >> > effective length (L), and material constant (E).
> The second step
> 		> >> > calculates AE/L, and checks if the connector
> stiffness is satisfied.
> 		> >>
> 		> >> >
> 		> >> >
> 		> >> > **Set 2: Bending Moment**
> 		> >> > Connector    Connector        Connector
> 		> >> > Strength      Moment(#-")     Stiffness(#")
> 		> >> > (input)         (output)            (output)
> 		> >> >
> 		> >> >  100%        1.38E6            infinity
> 		> >> >   99%         1.37E6           1.364E10
> 		> >> >   95%         1.35E6           2.620E9
> 		> >> >   80%         1.26E6           5.531E8
> 		> >> >
> 		> >> > Partial-rigid connection allows every connection
> strength to be
> 		> >> > adjusted. This example is applied to a bending
> moment.
> 		> >> >
> 		> >> > J.Luo
> 		> >> >
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