Equivalent radius of gyration

[tony1851]

Hi,
Quick question; I have a brick pier, cross-section shown in sketch (SI units). I've calculated the radius of gyration about its centroid; now need to find the thickness of an equivalent rectangular pier with the same value of R, for checking the slenderness ratio.
Would appreciate any pointers.
thanks.

 

[KootK]

Use the SQRT(I/A) definition to work your way back from R to b & d. You will need to set up the aspect ratio of the rectangular pier as a parameter. Curious, why not just use the pier's actual R since you already have it?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[tony1851]

Hi KootK,

I really need an equivalent effective thickness so I can work out the slenderness ratio - I would guess it would be around 250-300mm for a similar depth of section - but that's only off the top of my head.

It's quite a tall pier and I need to get the reduction factor as low as possible. Any suggestion as to how I could get the slenderness ratio knowing effective height and R?

many thanks.

 

[KootK]

If this is just a pin ended column, then the slenderness ratio is just: (height/radius of gyration). You probably want R calculated about a 45 degree axis to get the critical value.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[rb1957]

if you know I of your shape then you can easily calculate a circular area with the same I ... no?

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