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Partial rigid analysis is an advanced topic in structural analysis. Most
structural programs do not provide this feature. Some packages apply
"moment (or called member) release" to simulate partial rigidity.
However, moment release is not partial rigid connection.

Partial rigid connections allow the connection rigidity to be adjusted
between zero and full strength (100%). For example, an 3D member has 2
nodes, each of which has 6 dofs. Each dof has a connection rigidity.
Every connection rigidity (moment, torsion, axial force, and shear
force) can be adjusted. This can model a structure more accurately.

J. Luo

> ----------
> From: 	Y. Henry Huang[SMTP:hhuang(--nospam--at)]
> Reply To: 	seaoc(--nospam--at)
> Sent: 	Thursday, June 04, 1998 11:15 AM
> To: 	seaoc(--nospam--at)
> Subject: 	ALGOR, EAGLE, ETABS, STAAD etc.
> <<File: vcard.vcf>>
> I like to get response from members of this listserver (not limited to
> CA engineers please) on how the favorite frame analysis program of
> yours consider the rigidity of frame connections.  For the moment,
> let's focus on steel connections only. 
> I like to point to the AISC Manual of Steel Construction, Volume II
> Connections, 1st Edition.  On the Forward section, it stated, 
> "The behavior of a steel (my note, or R/C) frame depends on the
> behavior of the connection which, in turn, depends on teh connection
> design..........Connection behavior is usually defined by its
> moment-rotation relationship, Fig 1.  AISC classifies connection ... 
> ------------ASD----------LRFD 
> Rigid ----- Type 1 ------- Fully Rigid(FR) 
> Simple --- Type 2 ------- Partially Rigid (PR) 
> Semi-rigid - Type 3 ------ Partially Rigid (PR) 
> .......However, experience with certain connection design has
> demonstrated that a connection can be safely defined as rigid or
> pinned.  The analysis of the strength and behavior of structural steel
> connections is very complex and, considering the many simplifying
> assumptions made, the designer should avoid placing undue emphasis on
> an anlysis based on elastic theory in designing these
> connections........".  Then refernce were made to Section A2.2, B9 and
> J1.2, where the term "inelastic" appears. 
> Note that this handbook is not intended for Seismic Design. 
> Please comment on: 
> How you "design" connections? 
> How does the program you use handle the rigidity issue? 
> Y. Henry Huang