Research On Tapered Concrete-filled Double Skin Steel Tubular Beam-columns Under Hysteretic Behavior

Northwest China is rich in wind resources,there are a large number of wind power towers in this area.Tapered concrete-filled double skin steel tubular(CFDST)is considered in the use of the wind power tower.Because of this kind of towers have the following characteristics,such as the tower is towering,the slenderness ratio is large,bending behavior is good.This kind of towers are considered that the vertical load is small and the horizontal load is large,the bending moment of the bottom of the tower is larger than the bending moment of the top of the tower.At the same times,earthquake disasters occur frequently in northwest China,so it is necessary to study the seismic performance of buildings and structures.Whether wind load or seismic load can be simplified to reciprocating horizontal loads acting on the top of the tapered CFDST.Therefore,this paper reports the experiment research on tapered CFDST beam-columns under hysteretic behavior and the numerical analysis by the finite element software ABAQUS.The main works are as follows:(1)The experiment research on tapered CFDST beam-columns under hysteretic behaviorEight tapered CFDST beam-columns with different axial compression ratio and different hollow ratio under reciprocating load were tested.Two specimens with different hollow ratio and the same axial compression ratio under monotonic load were tested at the same time.The testing phenomenon and the failure mode of the specimens were described.The seismic behavior indexes such as rigidity degeneration,strength degradation,ductility index and energy consumption index were analyzed.(2)The numerical analysis on tapered CFDST beam-columns under hysteretic behaviorNumerical analysis models of tapered concrete-filled double skin steel tubular(CFDST)under hysteretic behavior were established by the ABAQUS software with the rational material model and concrete damage index were chose.The whole loading process of the tapered CFDST under reciprocating load were analyzed.The parametric analysis such as the axial compression ratio,the slenderness ratio,the hollow ratio,tapered angle,concrete strength and steel strength were studies to the influence law on hysteretic behavior indexes.The seismic performance was compared with tapered CFDST and uniform section CFDST,in order to find the equivalent section of uniform section CFDST can indicate the seismic performance of tapered CFDST.(3)The damage index of tapered CFDST50 typical experimental data of CFST,CFDST and tapered CFDST were collected to acquire the damage index model of tapered CFDST.According to the description of the experimental phenomenon in the literatures,the damage index of different degrees of damage and condition of damage were defined.These works can be the preparation and the theoretical foundation for the future research of coupling effect of other disasters after earthquake disaster.