Study On Load-Bearing Characteristics Of Double Layer Stirrup Confined Concrete Square Columns

Due to the low strength of concrete in the construction, column concrete members by axial pressure, the axial compression ratio is difficult to meet the requirement specification, so how to improve the bearing capacity and ductility of the concrete member, become the focus on the research topic at International and Internal. In recent years, the application of high strength concrete member more and more widely in the construction, because its brittleness than ordinary concrete, different between high-strength concrete and normal concrete.Based on this, the mechanical response of restraints on high strength concrete become very meaningful.In order to improve the ductility and seismic of concrete components, this paper presents double layer stirrup confined concrete columns use two layers of stirrup, inside and outside, to constrain the concrete. Analysis of the new type of concrete column on the experiment and theoretical.This paper has carried out the following research work:(1) We designed 18 double layer stirrups and 3 single layer stirrups on the axial compression characteristics of concrete square columns,from which a series of test data and patterns were obtained for double layer stirrup confined concrete square column. Using VIC-3D technique to measure the full two-dimensional deformation and strain, high-strength concrete is studied in this paper. Studied the VIC-3D test of high strength concrete square stirrups constraint measurement principle, the parameters of the mathematical analysis model is established. Dimensional strain is obtained by the movement of the speckle.(2) On the basis of the experimental datas and patterns,from the orthogonal experiment analysis, we analysis he distance between the internal and external layers of stirrup spacing.For the bearing capacity calculation equation for double layer stirrup confined concrete square columns,the first is stirrup spacing the third is inside and outside diameter of stirrup.(3) Put forward the relation of double stirrup restraint peak intensity and strain of the concrete column.Through the stirrup test datas, it is concluded that the strength of the single-layer stirrup increases with the hooped eigenvalue and larger, and improved the relation between the amplitude and the stirrup characteristic value. Within the inner restraint coefficient of concrete strength increase and established the relationship between the stirrup reinforcement characteristic value; Build he relationship between double square ductility coefficient and hooped reinforcement characteristic value, double match hoop constraint coagulation can improved the ductility coefficient of concrete greatly.(4) Build axial force-deformation relationship of confined concrete components.The model can reaction test of high strength concrete square stirrups constraint relationship between load and deformation, using the model simplely and conveniententmeet with the measured in experiment, considering influence factors comprehensively, it provided the basis of the use of double high strength square stirrups. which can be provided for the structural design of double layer stirrup confined concrete square columns. Double layer stirrup confined concrete square columns can be provided the reference of stirrup constraint and nonlinear analysis of structure.