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RE: Partially rigid connection design

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Concise, to the point and very well said!

Bill Cain, S.E.
Oakland, CA


		-----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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