An Experimental Study On Hysteretic Behavior Of Square Concrete-Filled Thin-Walled Steel Tubular Column With Internally Longitudinal Stiffeners

The effect of local buckling on the whole behavior of square concrete-filled thin-walled steel tubular columns should be considered when making research on their aseismic performance. The thesis chooses two section types with internal longitudinal stiffeners in order to improve the local stability of the thin-walled steel tube and its constraint ability on the core concrete. Nine square concrete-filled thin-walled steel tubular columns with stiffeners have been experimentally investigated in order to get their hysteretic behavior. The detailed analysis for the experiment process and its results has been conducted, and some academic research is also explored in this thesis. The main contents are listed as follows:1.) Nine square concrete-filled thin-walled steel tubular columns with stiffeners (six specimens with longitudinal stiffeners in two directions and three specimens with longitudinal stiffeners in one direction) have been experimentally investigated under combined constant axial load and lateral cyclic load in order to get their hysteretic behavior. The production of specimens and experimental methods are described in detail, and the experimental phenomenon is also summarized and concluded. The mostly important influence factors of hysteretic behavior, such as: the different forms of internally longitudinal stiffeners in the tube cross section and axial load ratio are considered in the design of specimens.2.) The results of the experiment have been analysed and compared, which includes the rule of hysteretic behavior, axial shortening, stiffness decay, energy dissipation, skeleton curve, ductility and bearing capacity. The test results show that the columns with longitudinal stiffeners in two directions have a better aseismic performance. The axial load ratio is the key influence factor for the hysteretic behavior, and the hysteretic behavior deteriorates obviously with the increase of axial load ratio. So the limit of axial load ratio of concrete-filled thin-walled steel tubular column should be reasonably determined.3.) Based on the experimental results. A simple calculation model on skeleton curve of concrete-filled thin-walled steel tubular column with longitudinal stiffeners in two directions is presented. The skeleton curves by calculation correspond with experimental results quite well. So the method can be used to...