Research On Hysteretic Behavior Of Circular Hollow Steel Tube-Reinforced Concrete Columns

Circular hollow steel tube reinforced concrete columns is a new type of structural member with good development prospect.Nowdays,the research is still in its infancy,especially,the research on seismic performance is still relatively blank,considering its potential application advantages and prospects in the field of engineering.In this paper,the hysteretic behavior of hollow steel tube reinforced concrete columns under low cycle reciprocating load is studied in two aspects of experiment and theory.Systematic analysis of the factors affecting the hysteretic performance,based on this,puts forward the hollow steel tube reinforced concrete columns P-?hysteretic model,the following works are carried out concretely:(1)In this paper,the experimental study on hysteretic behavior of 8 circular hollow steel tube reinforced concrete columns,2 reinforced concrete thin-walled members and 2 steel tubes is carried out with the cross section and axial compression ratio as parameters.The experimental study shows that under the conditions of different axial compression ratio,the failure modes of the hollow steel tube reinforced concrete columns are basically the same.P-? hysteresis curve is full,energy dissipation capacity.P-? hysteretic relationship skeleton in bearing capacity,stiffness and ductility has a good performance,and compared with the reinforced concrete thin-walled members and ordinary steel are improved.(2)On the basis of the stress-strain relationship model of steel pipe,steel bar and wrapped concrete under monotonic and reciprocating stress.Using the numerical method of hollow concrete filled steel tube composite column columns P-? and M-? hysteretic curves are calculated and analyzed.The theoretical results are in good agreement with the experimental results,the stress distribution of each part of the component in the whole stress process is analyzed by the model,The failure modes are basically consistent with the experimental phenomena.(3)Through the ABAQUS numerical simulation and the comparison with the test results,the constitutive relation and the model established are verified.Based on the analysis of expansion parameters,discusses the concrete strength grade,pipe diameter,longitudinal reinforcement ratio,longitudinal reinforcement yield strength,steel yield effect of pressure ratio on the circular hollow steel tube reinforced concrete columns P-?hysteretic relationship skeleton curves of mechanical properties of strength and axis.The analysis shows that the concrete strength,longitudinal reinforcement ratio and axial compression ratio on the hysteretic component of the P-? skeleton curve influence.(4)Based on the systemic analysis of parameters,the hollow steel tube reinforced concrete column P-? hysteretic model practical calculation method is proposed.The accuracy of the hysteretic model is verified by a typical example.