Research On Axial Compression Performance Of Concrete Square Columns With Circula Spiral Composite Stirrups

The seismic performance of the structure is an important factor in considering the safety of the building."Strong columns and weak beams,strong shear and weak bending,strong nodes and weak members" are the basic principles of seismic design of frame structures.The "strong column weak beam" refers to the column should be destroyed later than the beam,because the beam damage is a local component damage,the impact on structural safety is limited,and the damage of the column may lead to the collapse of the entire structure,may there will be serious consequences such as casualties and economic losses,so improving the load-bearing capacity and deformation performance of the column is critical to structural safety.Compared with square stirrups,circular spiral hoops have uniform stress and greater restraint strength.Therefore,the study of the unfolding axial pressure of the constrained square column of circular spiral hoops has great theoretical support for future engineering practice value.The main research object of this paper is a circular spiral composite hoop with an inner layer of a circular spiral hoop and an outer layer of a common square hoop.11 constrained square column models are designed,and the finite element software is used to simulate the axial compression test of constrained members.The simulation data explored the axial compression performance of ordinary strength concrete square columns constrained by high-strength circular spiral composite hoop.The four variables were explained in detail from the four aspects of stirrup strength and spacing,concrete strength and stirrup configuration.Stirrup restraint performance relationship.In addition,by collating the axial compression test data,the relationship between different restraint forms and the longitudinal strain,stirrup strain and concrete strain of the members and the effect on the yield of the steel bars were studied.The results show that the strain growth rate of the concrete,outer and inner stirrups,corners and middle longitudinal reinforcement of the circular spiral composite hoop are increased compared to the square composite hoop and cross-shaped hoop,and the peak value of the constrained column.The load is also the largest among the three types of couplings,indicating that the deformation and the bearing capacity of the member are better.The stirrup strength and spacing,stirrup configuration and concrete strength are all closely related to the axial bearing capacity and ultimate strain.Finally,from a mechanical point of view,the confinement mechanism of the circular spiral composite hoop is discussed in depth,and on the basis of the axial compression calculation formula proposed in the specification,the axial compression bearing capacity calculation method of the circular spiral composite hoop constrained square column is improved.