| Concrete Filled Rectangular and Square Steel Tubular Column (CFRC) structurehas a good ductility, plasticity, anti-earthquake, and so on. While concrete-filledcircular tubular structure takes on a lot of inconvenience in engineering design,construction and application because of it's particular section. So CFRC structurebecomes the representation of multi-story steel-frame structures. But at present, it isseldom used in China, just because of the less of corresponding codes and regulationsabout joints, and the less of related theories. This kind of structure is difficult to bepopularized.To coordinate the expansion of CFRC structure and the implementation of newdesign code, the three main theory in calculating concrete filled rectangular andsquare steel tube are discussed, together by the experiment results of supersonic flawdetecting, the superposition theory is verified to be suitable for the calculation ofconcrete filled rectangular and square steel tube columns. This paper analyses thestatus of research on calculation theory of CFRC in China and pointed out a problemneeding to be settled, namely the problem about distributing coefficients of axialpressure. Then this paper introduces two methods about distributing coefficients ofaxial pressure in CFRC, and compared them with facts. Lastly according tocorresponding distortion the author deduces a new kind of method about distributingcoefficients of axial pressure, and presents some correlated data to prove therationality of this new method. The calculation method adopted by Japanese code isanalyzed, for it is also in the superposition theory. According to rules of simplecalculation, clear concept and reliable safe, the calculation method of concrete filledrectangular and square steel tube columns is suggested.The state art of joints in CFRC structure is introduced firstly. Based onthrough-beam style joints in Japan we bring forward through-diagram style joints.Then the author designs a static experiment of this kind of joint. This experiment hasten specimens, one of whose column is hollow tube. The specimen whose column ishollow tube is used to compare with other specimens. Before this experiment, wehave carry on the material experiments of steel and concrete. Based on analysis inANSYS, we adopt that the radius of the connection of beam and diagram is 25mm.Moreover we calculate the load bearing capacity of the tested joints in theory. Afterthe experiment, this paper introduces the experiment of this kind of joint under staticloading and contrasts the result of this experiment to the result in theory in order totestify the reliability of calculation theory. According to the results of strain gauges,this paper analysis the strain distributing status of this kind of joint.In order to analysis the anti-earthquake ability of this kind of joint, the authordesigns a quasi-static experiment of this kind of joint. The experiment has threespecimens, one of whose column is hollow tube. The specimen whose column is hollowtube is used to compare with other specimens. This paper describes the failure process andfeature of each specimen. Based on the data got from the experiment such asmeasured hysteretic hoops, this paper makes a thorough comparison and analysis onthe index of seismic behavior such as load bearing capacity of the joints, ductility,energy dissipation, strength degeneration. The analysis results show that theconstruction details of diagram-through style joint are simple and reasonable and thisnew joint has a good seismic behavior.At last, the author puts forward several problems of CFRSST structures to beresearched more deeply and makes an expectation of CFRSST structures.
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