Abstract
This paper discusses the restoring force characteristics of Steel-Hoop-Concrete (SHC) composite column. Cyclic-loading experiments in which the point of inflection is fixed are generally carried out in order to estimate the restoring force characteristics of SRC or RC column. But at the time of earthquake, top end and bottom end of column get independent end rotations, and the point of inflection moves in column. Considering that there is few bond between concrete and steel in SHC column, the restoring force characteristics of SHC column cannot be sufficiently estimated only by the above experiments. So the following experiments were carried out. The experimental parameters are the amount of hoop reinforcements and compelled end rotation history. Nine specimens of 21 cm × 21 cm cross section and 80 cm length were tested. H-shaped steel (SS41, 150×100×3.2×4.5) was encased in each specimen and the compressive strength of concrete was about 450 kg/cm^2. The experimental results were examined analytically using Degrading Stiffness Tri-Linear Model (D-Tri Model) and Giberson's End Spring Model. The following conclusions were obtained in this study. (1) The ultimate strength of SHC composite column can be roughly estimated by additional theorem. (2) The restoring force characteristic of SHC column with sufficient hoop reinforcements are stable even when the independent compelled end rotation histories act on both ends of column. (3) The restoring force characteristics of SHC column can be roughly formulated by using D-Tri Model when end rotation histories of both ends of column are the same. (4) The restoring force characteristic of SHC column can be roughly formulated by using Giberson's End Spring Model except for the case that the uniform bending moment act on the column.
