The behaviour of continuous stanchions

Abstract

A description is given of tests carried out on small-scale steel stanchions of rectangular and ɪ -section subjected to the arrangements of load encountered in building frames. Two main types of loading are distinguished according to whether the stanchion is bent in single or double curvature. A theoretical explanation of the results observed is sought by reference to the simple plastic theory in which it is assumed that sections plane before bending remain plane after bending. The theory of members subjected to combined bending and axial load in the partially plastic range is developed, and is applied to the case of single curvature stanchions. The growth of the plastic zones is traced up to the stage at which complete plasticity occurs at three sections in the stanchion, and satisfactory agreement is obtained between the theoretical and observed collapse load. When the simple plastic theory is applied to double-curvature bending, inaccuracies arise in certain cases due to strain reduction in the plastic zones, and the simple theory is therefore elaborated to take account of the irreversible nature of plastic strains. The improved theory is then applied to appropriate cases of double-curvature bending.