Stresses in bracings due to lateral torsional buckling of beams

In structural engineering slender beams with I-sections are often supported by bracings. For the determination of the brace stresses due to the support, geometric imper- fections can be applied to the supported beam in order to obtain an equivalent load. These im- perfections are given in EC 3 for example. This approach is appropriate for beams with only positive or only negative bending mo- ments. For structures with negative bending moments at the beam ends and positive bending moments in midspan, as for example for the beam of a framework, the procedure using the equivalent imperfections does not provide realistic results. The load bearing behaviour for beams with negative bending moments at the ends will be presented in this essay. Details on how equivalent imperfections should be applied and on the determination of brace stresses will be pointed out. Furthermore the influence of the rotational stiffness of adjacent members on the beam stability and the brace stresses will be investigated.