steel structure Why does the length of beam section affect the twisting angle or torsion?
The relation ship is
Beam Torsion Angle = (T*L)/(J*G)
Where T is the applied torsion, L is the length of the beam, J is the torsional stiffness of the section and G is the shear modulus of the material.
So the torsional angle is directly proportional to the beam L. I.e. doubling the beam length doubles the torsional angle.
Hi
d(torsion angle) / d(length) =cte
thus:
torsion angle / total length = constant.
in the length: arc length = shear strain* d(length) (1)
in the length: arc length = radius*torsion angle (2)
1 = 2 results torsion angle = T*L/(G*J) according to shearing strain = shearing stress / G.
best regards.
Explanation in closed form analytical model are presented by previous two answers. In brief, the length of a OPEN SECTION (i.e. steel beam) will determine the resistance of the section to rotate in its weak axis. Take a long ruler in horizontal position with its major axis point upward and try pressing the free end downward. You will observe the ruler starts to twist. That is LTB. If you try to restraint the beam from moving sidewards along the length, the resistance to LTB increases.
Hello,
your question is quite unclear to me: Which kind of torsion do you have in mind? (Saint-Venant or with warping?)
What exactly do you mean by "the length of beam section"? The length of the beam or its diameter?
What's the background of your question?
Good question.. Please share me the best answer might you trust...
Regards…
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