Analysis of spiral stairs supported on a central column

Abstract

A method is proposed for the analysis of a central column supporting uniformly loaded cantilevered stairs. Equations for determination of bending moments about two perpendicular axes for hinged and fixed support conditions are given. Tabulated results for these moments and their resultant are presented for the range of spiral turn angles encountered in practice. Maximum resultant span moments obtained by means of the Newton-Raphson method are also given in tabular form. Finally, the method is illustrated by a numerical analysis of three-storey spiral stairs.