i-beams torsion and warping

huangyhg

i-beams torsion and warping
hi,
i'm working with bs5950 and i'm not clear about how to design against warping and torsion! details are given about lateral torsional buckling but nothing resembling vlassov or st venants torsion seems to be taken into account.
an tips on where the formulas are for determining that torsion and warping will not occur?
all the best
joey
when i was working in the uk, i came across a very good design guide for torsion in open sections it was by the steel construction institute i think.
check out this link
torsion and warping will occur, under twisting moment.  what you want to do is keep the stresses induced by the torsion, combines appropriately with flexure and shear, to below the limit.  at a given point in an i-section, torsion induces both additional normal stress and shear.  you will need to account for the additional flexural stress from the warping component of the torsion, and add that to your bending stress, and the additional shear stress due to warping and st. venant's torsion and add that to the shear stress due to bending.  you don't necessarily have to analyze the section separately for torsion, though some codes will take this approach.
you know everytime i hear anything related to st. venant or a prandlt analysis, i break out in hives.
download aisc design guide 9
if you are working to bs5950 i would second csd72's recommendation.  a most useful guide.