Abstract

Introduction

Conclusion

Data Availability

Conflicts of Interest

Acknowledgments

References

Copyright

Abstract

A new type joint of Circular Tubed Steel-Reinforced Concrete (CTSRC) columns was designed in this paper. The structural characteristics, manufacturing process, and mechanical properties of raw materials of the new joint were introduced. In order to simulate the earthquake action, two joint specimens were subjected to low-cycle cyclic loading at the end of the column. Based on the in-depth study of the failure characteristics, load-displacement hysteretic curve, skeleton curve, ductility index, load-strain hysteretic curve in the core area of the joint, energy dissipation performance, strength and stiffness degradation performance, and shear deformation in the core area of the joint during the whole loading process, the seismic behavior of this new type of joint was investigated. The results show that the new joint has reasonable failure characteristics, high bearing capacity, good ductility, excellent seismic energy dissipation performance, and strong resistance to strength and stiffness degradation, which meets the seismic design principle of “strong joint and weak component” and is suitable for the results with special requirements for seismic performance. In addition, preliminary design recommendations were put forward. The research results of this paper can provide a theoretical basis for the application of this kind of new structure.

۱٫ Introduction

At present, steel-concrete composite structure has been widely used in the field of civil engineering construction. Concrete-filled steel tubular column and steel-reinforced concrete column are two main forms of steel-concrete composite structure. The concrete-filled steel tubular column makes the concrete in the tube in a three-dimensional compressive stress state through the circumferential restraint effect of the outer steel tube on the concrete in the tube, so as to improve the concrete strength and the bearing capacity of the structural column [1–۳]. Steel-reinforced concrete column refers to the column concrete, equipped with steel, and with a certain stress and structural reinforcement, steel-reinforced concrete column through the synergistic effect of steel and concrete gives full play to the performance of the two materials and at the same time has excellent seismic performance and good economy. At present, it is widely used in high-rise and superhigh-rise buildings [4].

But the shortcomings of the two are also very obvious. The axial load shared by the steel tube and concrete is easy to cause the buckling of steel tube plate, leading to the decline of seismic performance of columns. Steel-reinforced concrete column is not convenient for concrete pouring because of setting steel skeleton and section steel at the same time, and the steel skeleton has insufficient constraints on concrete, which leads to low axial compression ratio limit and cannot make full use of material properties.

Therefore, on the basis of long-term engineering practice, experience accumulation, and previous research results, a new type of composite structure column has emerged: Circular Tubed Steel-Reinforced Concrete (CTSRC) column. Its outer steel tube is disconnected at the beam-column joint and does not pass through the core area of the joint. Therefore, its steel tube does not directly bear the longitudinal load but only restrains the core concrete, as shown in Figure 1. Research by relevant scholars shows that [5–۷] the CTSRC column has high compression and shear bearing capacity, superior seismic performance, strong interlayer deformation capacity, good fire resistance, and convenient construction and can make full use of high-strength material performance.