Mechanical Performance Research On Joint Of Concrete-Filled Cold-Formed Steel Multi-Limb Section Column And Beam

When design a steel structure,the beam to column joint is the key part which will influence the stability of the whole building.So a reasonable form of joint will improve the mechanical behavior of the whole structure.In this paper,a new type of beam-column joint,named top-bottom angle steel bolted connection,is proposed.This type of connection is used to connect the cold-formed steel column with concrete in it and an H-shaped steel beam.The column is composed of three kinds of different sizes cold-formed C section steel.The mechanical performance of this kind of joint is studied in this paper,and the simplified formulas for calculating the ultimate moment bearing capacity and initial connection stiffness of the joint are presented.This paper uses the finite element analysis software,Abaqus,to fine finite element simulation of the joint.The main variables of this paper are the thickness of the angle steel,the thickness of web angle steel,cold-formed C section steel’s thickness,bolt number of web plate,bolt diameter and strength,axial compression ratio and the concrete strength,under the cyclic load,the earthquake resistance behavior effect of the selected elements to the model is determined.According to the hysteretic behavior and the skeleton curve,the bearing capacity,ductility energy-dissipating capacity become better with the increase of axial pressure.When the axial compression ratio reaches 0.7,the bearing capacity and ductility of the joint decrease,which gives an explain that this kind of joint cannot resist the axial compression which is more than 0.6.While the thickness of cold-formed steel increasing,the bearing capacity and energy dissipation capacity shows up gradually,but the ductility has little change.As the strength of concrete,the thickness of angle steel and the number of web bolts go up,the bearing capacity,energy dissipation capacity and ductility have little change.With the increase of bolt strength and diameter,the bearing capacity and energy dissipation capacity increase.The bearing capacity and energy dissipation capacity increase with the increase of the number of top and bottom angle bolts,but the ductility decreases when the number of top and bottom Angle bolts increases to 3 rows.Four factors are carried out which are respectively the thickness of cold-formed steel,bolt number of the top-end angle steel,linear stiffness of beam and column and axial compression ratio.By using the differential analysis method of orthogonal design,the influence of the ultimate moment bearing capacity and the initial connection stiffness is calculated.The results show that the thickness of cold-formed steel has the greatest effect on the initial stiffness,and the number of bolt rows of top and bottom angle steel has the greatest influence on the ultimate moment bearing capacity.Using the regression analysis method,the effective of the factors to the joint come out.The relationship between the ultimate moment bearing capacity and initial connection stiffness and the four selected factors is derived by adding the one-way load,and the regression formula for calculating the ultimate moment bearing capacity and initial connection stiffness is obtained.