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Angle Brace in Compression

Angle Brace in Compression

Angle Brace in Compression

(OP)
Are there any aids in designing these?  Spreadsheet?  Software?  I do theses all the time and I am about to work out my own spread sheet.

RE: Angle Brace in Compression

That is exactly what I did......wrote my own spreadsheet.

RE: Angle Brace in Compression

LRFD 3rd has tables already made for concentrically loaded.

RE: Angle Brace in Compression

When a single angle is concentrically loaded the capacity is basically a L/rz issue.  Typically the problem for me however is something similar to example 10 p.3-55 in the ASD manual.  I don't know of any software to do this, so am currently working on a mathematica worksheet myself.  If anyone has any helpful hints or other resources, please post.

Regards,
-Mike  

RE: Angle Brace in Compression

For allowable stress design, see AISC Engineering Journal, second quarter 1991, "Tables for Equal Single Angles in Compression" which assumes situation where axial load is applied on one side by a gusset plate.  I use this all the time for miscellaneous braces,  For LRFD, same loading situation, see third quarter 2001, "Tables for the Design Strength of Eccentrically-Loaded Single Angle Struts".  

RE: Angle Brace in Compression

Thanks mrengineer and dik for the info.

-Mike

RE: Angle Brace in Compression

Check out the new AISC Spec Chapter E. There are new provisions for these.

14159

RE: Angle Brace in Compression

We wrote a nifty spreadsheet to do equal or unequal leg angles per the AISC LRFD Single Angle spec -

It really isn't that difficult to do and as SperlingPE says, the design is done quite often for braces and other such concentric angles - but with the spreadsheet, we added moment as well.

It worked out easier (of course) to use the geometric axis criteria instead of the principle axis way.

RE: Angle Brace in Compression

It seems to me that principal axis bending would be the controlling condition unless there is some lateral restraint permitting only x or y bending.  Otherwise you need to calculate stresses about principal axes, and angles don't have much in terms of z-axis bending.

-Mike

RE: Angle Brace in Compression

Our structural analysis/design package, Space Gass (www.spacegass.com), allows you to nominate eccentric end connection geometry for equal and unequal angles, i.e. 'long leg' or 'short leg' connected.

Does your package have the same feature?

RE: Angle Brace in Compression

I've briefly used RISA and am currently using Multiframe.  From what I remember RISA checked only kl/rz but was clear about what it was doing.  Multiframe checks combined stresses for x & y bending when a beam member is assumed, and checks kl/rz only for truss members.  In fact the reason I'm doing the Mathematica worksheet I mentioned before is to do the single angle calcs (from Multiframe) correctly as principal axis bending, or at least that's the way I see it.

I wonder if any of the other analysis/code checking programs do this right, apparently like Space Gass does.

A question for 14159, and others.  Does Chapter E in the new spec look like an improvement to the ASD 9th edition?  Would this be the way to go for writing a program now?  Actually it probably won't be law for another year or two the way things go.

Regards,
-Mike

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