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RE: Partially rigid connection design

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> ----------
> 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