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Curved Beam Torsion - Blodgett

Curved Beam Torsion - Blodgett

Curved Beam Torsion - Blodgett

(OP)
thread507-147144: Curved beam analysis

Can anyone verify the formulae in the back of Blodgett for torsional moment for a beam curved in plan subject to a uniform load.

I cannot seem to get the same values for A and B listed in the table using the provided formula. α seems to be in degrees, but I cannot get the numbers.

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RE: Curved Beam Torsion - Blodgett

http://books.google.es/books?id=t3nIySfmTk8C&pg=PA848&lpg=PA848&dq=viga+balc%C3%B3n+momentos&source=bl&ots=gKgCn8mgWy&sig=w6jZG-0a5CjwcICdCUq_OZDMTxY&hl=es&ei=GFFYTJbKJMyG4gbOgo3XBg&sa=X&;oi=book_result&ct=result&resnum=3&ved=0CB4Q6AEwAg#v=onepage&q=viga%20balc%C3%B3n%20momentos&f=false

What is interesting in the quote above is that the torsor at fixed ends (flector as well) depend on the mechanical properties of the section, hence the table will have been made for a set of sections for which the relative rigidities keep quite constant along the series of shapes.

Respect the formula I have tried once and didn't meet the result but may do it again later.

RE: Curved Beam Torsion - Blodgett

The formulas are OK, but whenever you multiply by an angle like that, it must be in radians.  If you convert the angles to radians and punch it out, you get the listed values EXCEPT for the first one for A (6 degrees) - there's one too many zeroes in his tabulated value.  Also, the formula for B spits out negative numbers, but he tabulates them as positive (a frame of reference issue - doesn't affect the values).

Note that the above is referenced from the last page of my copy of "Design of Welded Structures," Blodgett, 15th printing, 1996.  Yours may not have the tabulated error in it...

Also, you can work these problems using "Roark's Formulas for Stress and Strain."  In my 6th edition copy, the correct formulas can be found in Table 19, Case 1e.


-5^2 = -25  winky smile

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RE: Curved Beam Torsion - Blodgett

(OP)
I had previously tried using radians but did not get the same result. I think I was using radians all through instead of only when multiplying with α

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