端部带拉筋方钢管混凝土柱-钢混凝土组合梁框架结构抗震性能试验研究

“柱铰”是造成结构垮塌的主要因素。采取必要的结构构造措施在不增大结构刚度的基础上避免“柱铰”的形成是一个亟待思考与解决的课题。为提高钢管混凝土组合框架结构在地震荷载作用下的抗震性能，提出了一种柱端带拉筋方钢管混凝土柱-钢混凝土组合梁框架结构体系。通过对普通及端部带拉筋方钢管混凝土组合平面框架结构进行水平低周反复荷载试验，研究了柱端拉筋与梁柱抗弯承载力比对组合框架结构滞回性能、变形能力和破坏模式的影响。研究结果表明：两类组合框架结构均具有较好的抗震性能和耗能能力；试件的破坏模式主要有钢管局部屈曲、混凝土板开裂和钢管撕裂等；端部带拉筋方钢管混凝土组合框架结构的承载力与耗能能力优于普通方钢管混凝土组合框架结构；柱端拉筋能延缓结构塑性铰的出现，提高结构抗震耗能性。研究成果可为钢-混组合结构体系在抗震设防高烈度地区和城市人口密集区域的推广应用提供参考。

Experimental study on the seismic performance of terminal stirrup-confined square CFST columns to steel-concrete composite beam frame structures

The column-hinge of the frame structure was the primary cause resulting in the structural collapse. It is necessary to take structural measures to avoid the early formation of column-hinge and have no conspicuous effect on structural rigidity. In order to improve the seismic behavior of concrete-filled steel tubular (CFST) frame, a new composite frame system for terminal stirrup-confined square CFST columns to steel-concrete composite beams was proposed. A CFST frame and such a frame with further stirrup confinement in the CFST columns was conducted under vertical axial loading on the columns and lateral cyclic loading at the beam end. Several indexes that could reflect the seismic behavior of the new composite frame, such as the hysteretic performance, deformability, and the failure modes of the composite frame were analyzed. The test results show that the tested composite frames exhibited favorable seismic performance. The main failure modes were the local buckling of the steel tubular, concrete failure with cracks and the fracture deformation of steel tubular. The ultimate bearing capacity and the energy dissipation capacity of the terminal stirrup-confined CFST frame were higher than the ordinary one. The terminal stirrup welded in the steel tubular could delay the formation of column-hinge for the frame structure, and improve the seismic performance of the frame structures. The presented overall investigation may provide a reference for the design and construction of the steel-concrete composite frame structure located in high-intensity seismic regions and densely-populated areas.