Study On Bearing Capacity Of Concrete Columns Confined By Double Spiral Stirrups And Rectangular Stirrups

Confined Confined concrete can effectively improve the bearing performance and ductility of concrete.It is a new type of structural form with good economic benefit and broad space for development.In order to meet the actual demand of high bearing capacity and high ductility capacity in modern engineering structure,In this paper,a concrete columns confined by double spiral stirrups and rectangular stirrups is proposed that is a multi-constrained concrete structure with double helical stirrups on the base of ordinary rectangular reinforced concrete column.It can further strengthen the restraint of internal concrete,improve the mechanical properties of concrete columns,and reduce the cross-section area,etc.This paper focuses on the bearing capacity of this new column and mainly research work are as follow:1.The constraint theory model of concrete columns confined by double spiral stirrups and rectangular stirrups under axial compression is established based on the Sheikh’s effective constraint model theory.Based on the calculation theory of confined concrete,the calculation method of axial compression bearing capacity of this concrete columns has been deduced by unified strength theory and superposition principle.The calculation method of axial load bearing capacity of concrete column under this constraint is derived.Based on finite element software ABAQUS,the numerical simulation of the new type of concrete column is carried out.The results show that the theoretical calculation values are in good agreement with the simulation values.2.The method of bending moment axial force correlation equation is adopted to deduce the calculation method of ultimate eccentric compression bearing capacity of this concrete columns by simplifying the relation equation of bending moment and axial force and establishing a linear model of bending moment curvature.In addition,the calculation method of the parameters of five variables in the analytic relation is given.The seven groups of specimens were simulated by ABAQUS software,and the bending moment curvature model was verified by using the load deflection data obtained.The results show that the theoretical calculation values are in good agreement with the simulation values,which indicates that the calculation method has certain reliability.3.Through ABAQUS simulation test,the concrete strength,stirrup spacing,stirrup strength,position coefficient,eccentricity and high width ratio were analyzed in detail to reflect the influence for bearing capacity and ductility of this new type of concrete column.The results show that the order of influence of parameters on ultimate bearing capacity under axial compression is: concrete strength > stirrup spacing > stirrup strength > position coefficient.In the case of eccentricity compression,the order of influence is: eccentricity > concrete strength > stirrup strength > stirrup spacing > high width ratio> position coefficient.