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torsion on a loose lintel supporting brick

torsion on a loose lintel supporting brick

torsion on a loose lintel supporting brick

(OP)
I am trying to check the torsion of a loose lintel vs the BIA-recommended limit of 1/16"....but I can't find the "J" of steel angle shapes for my T*rho/J formula.  Does anyone know where I can find J of angles?  Can I just take J=Ixx+Iyy?

thanks

RE: torsion on a loose lintel supporting brick

I can't remember the exact limitations of using J=Ix + Iy, but I don't think that holds true for open sections.

RE: torsion on a loose lintel supporting brick

The AISC manual has a table of torsional properties for hot-rolled shapes.  See part 1 of the third edition LRFD, part 1 of the ninth edition ASD, or AISC design guide 9.  If you are outside of the US, you'll have to check your own references and manuals, but it shouldn't be a mystery.

RE: torsion on a loose lintel supporting brick

Note that Ix+Iy is the polar moment of inertia, not the torsion constant.

RE: torsion on a loose lintel supporting brick

(OP)
I didn't see J in part 1 of 2nd ed'n or 3rd ed'n of LRFD or J in ASD...J's not in there.

RE: torsion on a loose lintel supporting brick

Begin on page 1-117 of the 9th edition ASD or 1-89 or the 3rd edition LRFD.

RE: torsion on a loose lintel supporting brick

(OP)
ah!  gotcha...thank you

RE: torsion on a loose lintel supporting brick

For open sections (such as angles), the torsional constant J is equal to (1/3)*the sum of b*t^3 of all the pieces.

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