Stability and initial post-buckling behaviour of frame system with vertical bracings

Steel halls are assembled of plane thin-walled frames stiffened with vertical bracings consisting of two crossed rods in order to fulfil requirements concerning stability and stiffness of horizontal loads. In the paper, using stationary conditions of the total potential energy, a stability analysis and initial post-buckling behaviour of the construction are investigated. The hall construction is modelled by rigid plane frames, elastically connected on upper ends with the roof and in one or more spans with vertical bracings. It has been proved that the obtained bifurcation point is unsymmetrical and unstable, indicating that a reduction of the critical loads is possible due to some geometrical and loading imperfections.