Experimental Study On The Composite Column With Concrete Filled Discontinuous Steel Tube Inside And Its Joints

The composite column with concrete filled steel tube inside can provide great advantages over either pure steel or reinforced concrete members, as a kind of composite component, it has been increasedly used over the recent years. This dissertation is to research a new type of connection with strengthening ring of this column. Its distinct feature is that steel tube is discontinuous in the domain of strengthening ring, so the steel-bar of beams can be arranged continuously in order to transfer the moment of flexion. The axial load bearing capacity of the core area can be increased by the confinement of the strengthening ring. Due to the intermittence of steel tube, the cast of concrete and the lifting of the tube can be more convenient, the steel-bar in the strengthening ring can be prefabricated and the steel-bar in beams are continuous, avoiding site welding and hole in the steel tube.The experimental study on axial compression tests and reversed cyclic loading tests are presented in this dissertation. Load-deflection performance, typical failure modes, strain distribution and the energy-dissipation capacity of core area are observed and recorded. Based on the analysis of the distribution of stress and the load transferred way, mechanical modal and some calculating formulas can be given out, the resuming model can be established through the appropriate assumptions of hysteretic behavior, some design recommendations are also proposed. With the help of the existing research production, some achievements of the paper are as follows.Effective restrained radius of confined concreteA new prediction method of concrete local bearing strengthCalculation method for confined concrete with multiple lateral hoopingsThe bearing strength of composite column subjected to axial compressive loading Transverse reinforcement ration of composite column in critical state...