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staad pro 2000, modulus of subgrade reaction, etc.

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Arman,

I have used STAADPro in the past to attempt a design for spread
footings/mats, etc.  (I currently use STAADPro for steel design and analysis
but I do not use it for any foundation design/analysis which involves
bearing on soil.) 

Here is a major problem I have experienced with the software:

STAADPro does not release support springs for a soil bearing foundation when
those springs are in tension. Typically, a spring is assigned to a joint
that models the spring stiffness of the soil the foundation bears upon.
This can be accomplished by assigning spring support nodes directly or by
assigning a modulus of subgrade reaction, in which STAADPro assigns support
springs to the joints based on tributary area of the foundation bearing
surface to that joint.

In other words, if one has a spread footing with lateral forces and
overturning moments, there can be an occasion where some of the footing has
zero bearing pressure; STAADPro cannot distinguish this and instead allows
the spring to react in tension instead of releasing the spring from it's
reaction.  Other programs on the market can perform what STAADPro apparently
cannot.  One of these is RISA3D.

RISA3D allows one to assign support nodes as compression-only springs.  If
the spring encounters tension during the analysis, the spring is released.

Just my thoughts on this subject.....

DRM

-----Original Message-----
From: arman s rivera [mailto:asrivera(--nospam--at)edsamail.com.ph]
Sent: Saturday, October 07, 2000 7:06 PM
To: seaint(--nospam--at)seaint.org
Subject: staad pro 2000


i have also tried earlier versions of staad, and i agree with you about it
not being very user friendly.  but the staad pro 2000 version is quite
different.  it's graphical interface is quite easy to use.  aside from the
point and click capability, you also have the excel-type data base of the
joints and members info on screen so if you wanted to type in your input
rather than click on the joints or members, you could do that as well.

but still, i have experienced some glitches with it, like the zoom in and
out feature, to put it bluntly, it sucks!  

i have only heard of sap 2000, can you give me more info on this software?
i.e. website? cost?  it's budgeting season and who knows, maybe i can sneak
this into the purchase request sheet.

thanks.

arman


seaint(--nospam--at)seaint.org wrote:

>John is right. My experience has been that it is more hate than love
>relationship. I too have used staad since a long time ago. I could never
get
>its graphic user interface to work properly without having to go back and
do
>lots of other things to make it work. But that was before the Pro edition.
>This version may be more friendly, however, I have been using SAP2k for the
>past two years and have stated really liking structural modeling again! I
>use it exclusively in graphic mode and it works great.


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