I'm interested in how to work out whether torsional effects can be ignored or not, in calculating the adequacy of a given steel beam in the following idealised eccentric scenario.
Or, equivalently, the criteria which must apply, for it to be appropriate to treat the beam and its UDLs as a simple question about vertical plane bending, needing only to consider the actual vs design bending moment, deflection, and bearing support strength.
Description of problem
The problem is idealised and static, so the available parameters are the beam's inherent properties, the UDLs Load 1 and Load 2, and the length (clear span) of the beam. For simplicity, the beam can be deemed horizontal and both positionally and rotationally fixed at both ends. (It might be the top beam in a moment resisting frame, or both ends concreted into adjoining walls.)
Load 2 is one side of a massive and stiff horizontal rectangular object, such as a thick steel sheet or precast concrete floor, that's simply resting (unattached) on the bottom flange. (The other side of the sheet is simply resting unattached on a [relatively distant] parallel wall or second beam to the left). There are adequate stiffeners in the flange itself
If Load 2 is small enough, it will be contextually trivial and we can totally ignore the torsional element, and just treat the beam as subject to vertical bending only from Load 1.
If Load 2 is large enough, there will be a torsional dimension to the problem, requiring more complex calculations or numerical methods.
What method, criteria, or formula would be used to determine whether or not the torsional aspects of Load 2 can be ignored, for the purposes of calculating whether the beam is adequately strong for the setup and loads?
Or is it the case that enough stiffeners and the problem can be ignored?