Custom Shape Axial Capacity
Custom Shape Axial Capacity
(OP)
Hey All, (Likely Josh)
I've created a reinforced w-column using RisaSection, it calculated all the properties correctly (from what my quick hand check suggest). We are adding plates to the flanges to keep the shape symmetrical.
I've also successfully imported said section into R3D including all properties (J and Cw included). However, when checking the axial capacity it was in the range of 10x lower than my hand calcs suggest it should be. That is even with unbraced length set to zero.
So I then modelled just a very basic pinned column with a singular load, again unbraced length set to zero, and it returned a capacity 10x lower than expected.
Anyone ever come across this before? I've attached my test run.
In the end, this reinforcing is actually going to be applied to a pre-eng steel frame, however this axial capacity issue is causing the reinforced frame to be weaker than the original in the model. Which the hand calcs don't agree with.
I've created a reinforced w-column using RisaSection, it calculated all the properties correctly (from what my quick hand check suggest). We are adding plates to the flanges to keep the shape symmetrical.
I've also successfully imported said section into R3D including all properties (J and Cw included). However, when checking the axial capacity it was in the range of 10x lower than my hand calcs suggest it should be. That is even with unbraced length set to zero.
So I then modelled just a very basic pinned column with a singular load, again unbraced length set to zero, and it returned a capacity 10x lower than expected.
Anyone ever come across this before? I've attached my test run.
In the end, this reinforcing is actually going to be applied to a pre-eng steel frame, however this axial capacity issue is causing the reinforced frame to be weaker than the original in the model. Which the hand calcs don't agree with.





RE: Custom Shape Axial Capacity
RISASection is very good at calculating A, I, the plastic section properties and such. But, when it has to figure out what the thickness of a built up flange is, it can be difficult. We recognize this, though and give you (within RISASection) the ability to override these two values. See attached image.
My guess is that we interpreted the flange thickness as significantly too small. This would result in local buckling controlling the capacity of the member.
RE: Custom Shape Axial Capacity
RE: Custom Shape Axial Capacity
That appears to have solved it.
Thanks,