The buckling loads of unbraced PR frames under non-proportional loading

Abstract This paper discusses the elastic stability of unbraced frames with partially restrained (PR) connections under non-proportional loading drawing upon the concept of storey-based buckling. The problem of determining critical elastic buckling loads of the frames under non-proportional loading is expressed as a pair of minimization and maximization problems with stability constraints, and is solved by a linear programming method. A simplified manual calculation procedure is also presented for design practice. Upon adopting the end-fixity factor, the proposed method is comprehensive regardless of end rotational conditions of beam and column members, and applicable to unbraced frames with both partially and fully restrained connections. Critical buckling loads of unbraced frames with different beam and column end rotational conditions are investigated.