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Re: Partially rigid connection design

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>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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