Plastic neutral Axis of HSS round pipe filled with concrete 1

[hydraulicstr]

I am calculating the Allowable axial Load and Moment for HSS round pipe filled with concrete. AISC 13 shows equations based on Plastic stress distribution method. I don't know how to calculate Plastic neutral axis and Theta 2 based on that for my calculations. Any advice ??????

 

[Teguci]

Never done this, but I think I'd try something like the following:

The plastic tensile stress of concrete = 0. Go to concrete book and design concrete beam with pipe as reinforcing (compressive and tensile). To get a full picture of the beam-column's performance under different axial moment ratios you will need to construct a compression-moment interaction diagram (pg 436 of MacGregor for the step by step example).

Verify that the load is distributed to the concrete at the load and reaction points since you won't have deformations or studs to transfer shear (AISC Spec I6-3c)

 

[ernestog84]

This is covered in AISC Design Examples v14.1

AISC Design Examples


Look on Page I-6.

Every step is laid out for you.