Evaluation of STAAD.Pro VS other softwares

[Bill2001]

Hi,
Is this true that STAAD.Pro has some basic errors as follows?

STAAD.Pro does not take into account the eccentricity of the shear center of beam members and consequently you can't analyze asymmetric sections like channels or open cross sections where the CG and shear center doesn't coinside?

What about plate/shell elements? Does STAAD calculates section forces correctly compared to ANSYS or other FE programs?
I would like to have your experience analysis.
Thanks in advance.

 

[structuresguy]

I would suggest that you ask such technical questions directly to Staad's tech support. They should be able to give you the straight answer.

Also, if you need to do full 3D FEM, I would not suggest staad. Staad is good for flat plates of fairly simple geometries, like floor slabs, walls, etc... But if you are trying to model the stresses on a steel section due to loading on one flange only, or some 3D part like a welded bucket or bracket, well, staad would not be the best choice.

 

[gongaga]

What do you suggest in steel detailing analysis since staad isn't the best choice?

 

[JoshPlumSE]

Most structural programs assume that member loading is through the centroid and shear center. So, STAAD wouldn't exactly be alone in this regard.

But, when the shear center and centroid don't coincide then you have torsion in those members. I have yet to find a program that has a perfect solution.... At least not for WF or Channel type members.

The problem is that Torsional Warping plays a huge part in behavior of any Wide Flange or Channel shape. To my knowledge even the heavy duty mechanical type programs (Ansys, Marc, and such) do not properly account for the torsional warping effect on their beam elements.... though someone with experience with FEM ansalysis for Mechanical applications could probably address the issue more thoroughly.

In my experience, I've always put together a simple hand calculation to supplement the computer analysis when I begin to worry about this effect. The Salmon and Johnson book on steel design has some good hand calc methods related to an "equivalent tee" analogy. These methods are always conservative and are pretty easy to apply.... Better yet, they actually give you a pretty good theoretical understanding of the types of stresses that are produced from torsional warping and why.