Analysis of Helicoidal Girders

Helicoidal girders are becoming very common structural members in staircases, bridges, and ramps. Their structural analysis is cumbersome and difficult, and is often simplified from the case of a curved space girder to the case of a circular bowed girder. A few investigators have done some work on this problem, covering some special cases. The purpose of this study is not only to present an analytical method of analysis, but also to provide the designer with a set of design charts from which he can determine directly the redundants of a fixed-ended helicoidal girder of any given symmetrical cross section, slope, and curvature. In spite of the fact that these charts are limited to the case of a uniformly distributed load, they cover a multitude of cases that include a wide range of geometrical configurations.