Does ANSYS account for shear lag effect in beam models?

As we understand what you mean by shear lag, the answer is "no." A civil engineer explained to me the case of shear lag in a cantilevered I-beam structure. It is the transition of axial stress from the center of the flanges to the outer edges of the flanges from a shear load applied at the free end of the structure along the web. The outer flange edges pick up more and more axial load as you move towards the fixed end.

I made a shell model of an I-beam structure and a similar model using beams, and did not see the parabolic distribution of bending stress in the beam model that I got in the shell model (please see attached input files and bending stress

Therefore, the best approach may be to model everything with beams and then submodel the regions of concern with shell elements. Shells and solids (and SOLSH190 solid-shells) can do a lot that you just cannot get out of a beam model. In most cases, this shear lag effect is pretty small, especially for typically sized beam sections. For example, I-beams tend to have narrower flanges than the depth of the web. If the reverse were true, I suspect the shear lag effect would be morepronounced. In most applications, the shear lag effect can be neglected in relation to the other approximations made in FEA.

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