Command to control member shrinkage

[WARose]

If you have axially loaded members (i.e. externally applied load in kips)....is there a command to tell STAAD not to consider their shrinkage/elastic compression from a axially applied load?

Why we are on the subject, isn't there such a command for shear displacement as well? Thanks.

 

[JoshPlumSE]

What you describe isn't what I would call shrinkage, it's deflection due to the applied load.

There are ways to control what type of deflection occurs in a member. Say you have a beam that you want to be infinitely stiff in the axial direction. The axial stiffness of a member is AE/L. So, you can modify A, E or L to manipulate the stiffness.

To eliminate both shear and axial deflection, you could merely manipulate the member so that it has an extremely large Area (A). Though, if you do this you will want to make sure the density of the material is set to zero or else you will probably get an unrealistically large weight because of the increased area of the member.

 

[WARose]

Found the command for shear: Set Shear

If anyone finds the command for axial compression/tension....let me know. Will continue to look.

 

[SethGuthrie]

I don't think you can override axial deformation. You could make the section extra stiff (large E) and then assign a cracked factor reduction for bending (RIX, RIY, RIZ) I suppose.

 

[WARose]

thanks seth.

 

[Celt83]

I'd be more inclined to take Josh's approach and increase the cross section area and reduce the self weight to increase the axial stiffness. While Seth's idea of increasing the E would work also it would have additional impacts on the flexural stiffness of the members which I think you'd want to avoid if possible, which is what Seth's suggestion on adding crack factors would help get around. For me personally I'd find it simpler to do the area/self-weight modification.


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