beam element (cross section "general section") excentric beam

[artugan]

Hello,
I have a problem with declaring cross-section of excentric beam element with "general section" mode. Simply it does nothing to my beam. I declared cross-section geometry but errors appear and analysis is aborted. When I define some already prepared model from "pre-definied" menu it works, but I want to make excentric model of angel bar applied to plate element for stifness increase - not some C shape. It looks like "general section" menu is not applied for solver calculations. Maybe I forgot to declare something I don't know. I Hope somebody could help me with this.

[John_Holtz]

Hi,

I took a look at your model. I am not sure why the general cross-section is not working, so I have asked someone else to take a look at it. In the mean time, you may be able to use one of the shapes from the AISC library. It appears that your shape is very close to an L8x4x1/5 angle [4 inch (101.6 mm) x 8 inch (203.2 mm) x 0.5 inch (12.7 mm)].

The second thing to do, whether using a pre-defined shape or the general cross-section shape, is to use a beam offset. By default, the centroid of the theoretical cross-section is located at the line drawn as the beam element, so this places part of the cross-section above the shell and part of it below the shell. You want to specify the offset so that the theoretical centroid is the proper distance above the midplane of the shell.

Last, you may want to change the thickness of the shell. 15 m thick seems too large 😉

John Holtz
Product Design Engineer, Algor Simulation
Autodesk, Inc.

[artugan]

Yes units mistake 😜

But I've also changed as you sad my beam cross section to Lx8x4x1/2 applied offset 152 mm changed orientation and... "general section error analysis aborted". Little weird because I declared at this moment "pre-defined" sections. And when i change back to "general section" one of beams (only 1) appears after verification as my "general section" shape but others still are like "pre defined" (also this "general section" model does not need beam offset and changed orientation). Maybe it is something with layers? I'm still stuck here with this problem.
However working with "general section" mode is more comfortable for me because it gives me option of using different "L"s "P"s "T"s and "I"s that are used in hull construction that I'm trying to model ;] Maybe it's Algor wekness. If it is I hope new service pack could fix this.

[John_Holtz]

Hi, the problem with the general cross section is related to the layer number of the beams. General cross-section currently requires the lines to be on layer 1. A quick way to change them all is
1. right-click on the part in the browser
2. choose "Select Subentities > Lines"
3. right-click anywhere in the canvas
4. choose "Modify Attributes".
5. Set the Layer number to 1 and click OK.

John Holtz
Product Design Engineer, Algor Simulation
Autodesk, Inc.

[artugan]

Ok thank you everything now works well 😉