Punching Shear/Polar Moment of Inertia

[dcarr82775]

Anybody know of a reference for calculating polar moment of inertia of a slab around a column with openings in the slab? Also, similar question for columns that are hexagonal, thus a hexagonal critical perimeter. I have quick and dirty methods, but this requires something more precise.

 

[ToadJones]

Ip = Ixx+Iyy

 

[dcarr82775]

I should be more clear. I know how to calculate it without openings. I am making some assumptions about how to handle the openings and the non orthogonal sides. I am looking for a reference that will confirm (or not) my assumptions.

 

[mijowe]

Decon Studrails has free software that is used to specify their products. The software does a check for round and rectangular columns and also allows you to located openings in the slab around the column. If you put in you data and do not require rails it will let you know. I also believe it give you decent backup data that you could use to compare with.