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Torsional Constant T beams
- Thread starter aesoton
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btrueblood
Mechanical
The torsional moment of inertia is "J", my Roark's gives
a general formula
J = Ix + Iy = I1 + I2
Assuming x & y axes (or axes 1 & 2) are orthogonal.
Hopefully you have the equations for the moments of inertia for a T-section, or can derive them from rectangular equations and the offset axis theorem. I can try and write them out, but they get a little hairy, and defining some of the terms will be difficult without a diagram. I'm using _Roark's Formulas for Stress and Strain_, W. Young, 6th ed., McGraw-Hill, 1989; see page 63.
Ben T
a general formula
J = Ix + Iy = I1 + I2
Assuming x & y axes (or axes 1 & 2) are orthogonal.
Hopefully you have the equations for the moments of inertia for a T-section, or can derive them from rectangular equations and the offset axis theorem. I can try and write them out, but they get a little hairy, and defining some of the terms will be difficult without a diagram. I'm using _Roark's Formulas for Stress and Strain_, W. Young, 6th ed., McGraw-Hill, 1989; see page 63.
Ben T
The statement by btrueblood is incorrect: that formula is far from being true for open thin sections.
andrew299: look in the site below, under Beams -> Cross sections -> I beams -> Cut : by clicking onto 'Formulas' you'll see your formula.
And if you could avoid cross posting...![[nosmiley]](/data/assets/smilies/nosmiley.gif "[nosmiley] [nosmiley]")
prex
Online tools for structural design
andrew299: look in the site below, under Beams -> Cross sections -> I beams -> Cut : by clicking onto 'Formulas' you'll see your formula.
And if you could avoid cross posting...
prex
Online tools for structural design
I like to direct you to an excellent document published the AISC. It is Design Guide number 9 titled Torsional Analysis of structural steel members. You can buy/view this document on their web site
If you are a member, you can download it in PDF. The design guide is an excellent source and reading on torsional analysis. It is full of charts for various boundary conditions not to mention torsional constants for various steel shapes ready for use.
Good luck
If you are a member, you can download it in PDF. The design guide is an excellent source and reading on torsional analysis. It is full of charts for various boundary conditions not to mention torsional constants for various steel shapes ready for use.
Good luck
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