Abstract
This paper describes the newly developed loading apparatus for experimental studies to clarify the restoring force characteristics of reinforced concrete columns subjected to bi-directional horizontal forces and axial force. The loading method by this apparatus is as follows : 1) The base of column is fixed on the bed of loading apparatus. 2) The axial force is vertically applied by dead weight. 3) Two horizontal forces are applied to the top of column by oil jacks independently each other. In this loading apparatus, the relative three rotational displacements between top and base of column are restrained by the link mechanism, but the two horizontal displacements and vertical displacement are not restrained. Three specimens were tested without axial force, in order to obtain the fundamental data about the restoring force characteristics of reinforced concrete columns to bi-directional horizontal displacements and to examine the effects of the link mechanism on restraining rotational displacements. In this experiment, horizontal, vertical and rotational relative displacements were measured. From these experimental results, it was found that all rotational displacements were negligibly small, but horizontal and vertical displacements were not restrained by the link mechanism at all. Therefore, the loading apparatus developed here was operated properly and was restraining the rotational displacements, as was expected in its design. As a result, it was proved that the experiments of reinforced concrete columns subjected to bi-directional horizontal forces and axial force could be carried out on the clear conditions conveniently.
