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How to measure amount of twist

How to measure amount of twist

RE: How to measure amount of twist

You could put a square against the web to measure the flange tip displacement. Then use trig to work out the angle of twist.

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.

RE: How to measure amount of twist

(OP)
KootK (Structural),
Thank you for your idea, could you please draw a sketch show where I place the square?
The column is a long column.

I appreciate it if you can explain on sketch where exactly I place the square.

Thank you

RE: How to measure amount of twist

Could you span a string on the Center line of the beam on top of the flange and then measure the distance at maximum delineation?

RE: How to measure amount of twist

I'm not sure when I'll next have time to scan and post a sketch SKJ.

If the opposing flange is still straight, you could measure to that and subtract it from the known beam depth to work out the flange tip displacement.

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.

RE: How to measure amount of twist

SKJ25POL:
I assume that this twist or deformation is over some finite height of the col., and that the top and bot. of the col. are still in pretty good shape and in alignment. Clamp a bar to the outside of the flange at the top and bot., it should be a few inches longer than the flg. width. Then clamp pieces of piano wire btwn. the bars t&b and on their inside. Place the wires 1/8 or 1/4" out beyond the good flg. tips., so you are not touching the flg. tips anyplace. Now, you should be able to measure from the wire to the actual flg. tip in either x or y directions and at reasonable height increments over the deformation height. If the web is in pretty good shape, buy an inexpensive stl. square (but accurately square) and cut one leg short enough to fit btwn. the flg./web fillets. At the square corner of the square, cut a 45̊ clip off the square big enough to fit over the fillet radius. Place the short leg on the web and the long leg on the wire, and you should be able to measure the shape of the flg. deformation at any height interval. I think this is essentially what KootK was talking about.

RE: How to measure amount of twist

Obviously, this assumes that you can get to where you'd need to be to take the measurements.

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.

RE: How to measure amount of twist

Page 1-119 of the Steel Construction Manual, 14th Edition or page 1-149 of the SCM, 9th Edition.

Jim

RE: How to measure amount of twist

(OP)
Thank you every body and especially thank you KootK (Structural) for the sketch.
Appreciate it very much

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