Design of unbraced multi-storey steel frames

Simple approximate methods for analysis of unbraced frames have played a part in encouraging the use of steel in construction. These methods have been supported by research, to verify and to extend their scope. This paper questions their continued use and further development. It is appropriate to do this at the present time when documentation and software are needed to introduce the Eurocodes. Approximate methods still have a role, in initial design. For unbraced frames early consideration needs to be given to limiting sway in service conditions. A very simple formulation is presented, to enable section sizes to be determined to satisfy this criterion.