Mechanical Behavior Of Special-shaped Column Composed Of Concrete-filled Square Steel Tube-Eccentrically Braced Frame System

Special-shaped column composed of concrete-filled square steel tubes(the SCFST column)can hide the column in the wall,which has good architectural effect and mechanical properties,and has been widely used in residential buildings in recent years.In this passage,the stability calculation method of special-shaped column composed of concrete-filled square steel tubes is proposed,which has guiding significance for engineering design.At the same time,special-shaped column composed of concrete-filled square steel tube-eccentrically braced frame system which is suitable for high-rise buildings is proposed.The structure has good seismic performance and energy dissipation capacity.It has good engineering application value,and meets the national requirements for assembled buildings.The main researches of this paper are as follows:The formulas for stability of concrete-filled square steel tubular composite special-shaped columns under the action of axial forces and bending moments around asymmetric axes were investigated.The finite element model was established,and the experimental results,the finite element results and the results of stability formula were compared.The comparison results were good,and the formula was verified.The practical application of the SCFST column was introduced through a practical engineering example.The method and detailed construction of connection joints between the SCFST column and concrete beam was introduced.The SCFST column became a good choice in practical engineering.Two groups of quasi-static tests of SCFST column-eccentrically braced frame and one group of SCFST column-centrally braced frame were carried out.By the test,the damage mechanism of the structure was reasonable.Under the horizontal action,the energy dissipation beam section first yielded and formed plastic hinge,and the failure mechanism was reasonable.The hysteresis curve of the structure had no pinching phenomenon,and the system performed good energy dissipation capability and good deformation capacity.Compared with SCFST column frame-central braced structure,SCFST column frame-eccentric braced structure has better ductility and energy dissipation capacity.The finite element model of SCFST column-eccentrically braced structure was established.The failure mechanism of the finite element model was consistent with the test,and the bearing capacity,stiffness and test results were similar,which verified the accuracy of the finite element analysis.The finite element parametric analysis of SCFST column-eccentrically braced structure was carried out with the parameter of axial compression ratio,sections of columns and thickness of the brace.The results showed that the axial compression ratio had little effect on the bearing capacity of the frame;Increasing the section modulus of columns in the plane of the frame had great influence on the bearing capacity and rigidity of the frame;With the increasing of the wall thickness,the influence of the wall thickness on the bearing capacity and rigidity of the structure became smaller.