Study On Axial Compressive Behavior Of Rectangular Concrete Columns Confined With Three Spiral Stirrups

In order to combine spirals and rectangular concrete columns,a new type of stirrups configuration called The Three Spirals Stirrups was presented and studied.This new type of stirrups configuration consists of a rectangular hoop and a interlocking spirals.First of all,this paper has carried out the axial compression test on a banded composite stirrups concrete column with binding hoop and five rectangular concrete columns confined with three spiral stirrups,and its mechanical properties and failure characteristics under axial compression load are studied.The results show that the rectangular concrete column confined with three spiral stirrups with the same volume ratio have higher efficiency,peak strain,greater ductility coefficient and higher stirrups than the banded composite stirrups,and the stirrups are higher when the peak bearing capacity is higher The higher the stress value of the stirrups,the higher the peak load capacity and the peak strain,the smaller the spacing of the rectangular spiral stirrups,The higher the peak bearing capacity,the smaller the spacing of the circular spiral stirrups,the strain,peak bearing capacity,peak strain,ductility coefficient and residual bearing capacity when the bearing capacity decreases rapidly.The larger the average stress growth value of the stirrup is,the greater the ductility coefficient The larger the specimen has better deformation properties.Secondly,this paper presents the stress-strain curve of the compression of the concrete with three-screw stirrups,and compares it with the test curve to verify its rationality.In addition,this paper presents the formula of the indirect reinforcement area of the rectangular spiral stirrup.On this basis,the theoretical formula of the compressive bearing capacity of the three-screw stirrups is proposed,and the comparison with the experimental results shows that the calculation formula is reliable.Finally,this paper uses the finite element analysis software ABAQUS to carry on the numerical simulation analysis to the three-screw stirrup column,and verify the rationality of the finite element model by comparing the finite element calculation result with the experimental result.Based on the comparison between the finite element analysis results and the theoretical curves and bearing capacity calculations,it is further verified that the stress-strain relationship model of the three-screw stirrups under the axial compression load and the bearing capacity of the reinforced concrete rectangular cross-section columns The reliability of the formula.At the same time,the finite element analysis software was used to analyze the three parameters of concrete strength grade,circular spiral stirrup spacing and rectangular spiral stirrup spacing.The results show that the higher the concrete strength grade,the higher the peak stress of the reinforced concrete rectangular cross-section column,the lower the average value of the concrete strength increasing coefficient,the worse the strength of the concrete,The smaller the bearing capacity,the peak bearing capacity,the ductility coefficient and the residual bearing capacity.The larger the spacing of the rectangular spiral stirrups,the higher the bearing capacity,the ductility coefficient and the residual bearing capacity.And the design recommendations for the spacing of the circular spiral stirrups and the spacing of the rectangular spiral stirrups are given.