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RE: STAAD or RISA?

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Dave,

I am curious...what do you use the master/slave funciton for?  Is it
per chance to "model" the diaphram action in a 3-D model?  If so, you may
want to be a little careful with STAAD.  While they may have updated the
function, I do know that in older versions (not too old) the master/slave
could not be used to get a true rigid diaphram effect.  The master/slave
function makes ALL the slave joints translate the same as the master joint
in plane of interest.  The result is that using the master/slave method
will not allow for torsional rotaion of floor plane due to relative
stiffness of lateral frames/walls.  In otherwords, your model (if using
the master/slave function to model the diaphram) will be ignoring the
torsional effects of the lateral loads.

RISA does have a diaphram option that at least appeared (it has been a
while and I don't have RISA to use at this time) to include the torsional
effects.

HTH,

Scott
Ypsilanti, MI


On Fri, 6 Sep 2002, Dave Langhone wrote:

>
> I had to sign-up once James told me about this discussion. STAAD, baby! The flexibility you have in that program is amazing. It has the power of the free-form command file (unlike SAP or Strudl) and batch processing with great interface. You can do unlimited project sizes, multiple structures, vibrational analysis - can't in RISA. RISA is a nice program - but STAAD has the power and the user-interface. It is like a hybrid of the Incrdible Hulk and Wonder Woman (hee, hee!). We do a lot of multi-story parking structures - so I need the concrete design, master/slave and advanced plate elements - plate releases, pre-stressed loadings. The great thing is that I can make a change in so many ways - command file, Excel-like spreadsheets, graphically. We used to maintain a few packages but now have consolidated to STAAD.
>
> Go Mariners!
>
> Dave
>
> PRCE
>
>
>
> ---------------------------------
> Do You Yahoo!?
> Yahoo! Finance - Get real-time stock quotes


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