Study On Stress-strain Curve Of Full-Scale Specimen Of Confined Recycled Concrete

Recycled concrete is a new-type green construction materials,which can achieve favorable economic effect and social effect by being applied extensively in projects.During the actual design,analysis toward the force condition of the components can be carried out by utilizing various finite element analyzing software,which may involves the selection of the constitutive model of the materials.Therefore,the relative research on the constitutive model of the restraining recycled concrete may have the important practical significance of the project.In this test,restraining recycled concrete specimens which 3 types of the stirrup with different cross sections have been designed and manufactured.The mechanical performance of recycled concrete under various restraining conditions of the stirrup can therefore be studied by carrying out the axial loading test.During design of testing program,in premise of mix proportion that incorporates 50% recycled coarse aggregate,a group of incorporating 50% recycled coarse aggregate and 30% fine aggregate has been set in comparison.There,through changing loading rate,strength of longitudinal bars,reinforcement ratio of longitudinal bars,diameter of longitudinal bars,spacing between stirrups,volume ratio of transverse reinforcement,diameter of stirrups and stirrups configuration,influence of these variables would exert on mechanical performance of the restraining recycled concrete can be investigated,which may provide a reference for further research.Conclusions of experimental study can be indicated that: 1)loading rate may have effect both on strength and deformability of restraining components;that strength of restraining recycled concrete components may be improved with relatively high loading rate,while it may weaken the deformability;2)the strength of components that incorporate 30% fine aggregate decrease,as well as deformability is relatively poor;3)with same longitudinal reinforcement ratio,components that adopts longitudinal with minor diameter may have a relatively favorable mechanical performance,while this effect may not be evident for components utilizing HPB300 stirrups which HRB500 high-strength longitudinal reinforcement bars have been adopted either;4)with same volume ratio of transverse reinforcement,deformability of components can be largely effected by the diameter of stirrup,there,stirrup spacing valued 50 mm are recommended under equal conditions.Additionally,3 types of the restraining constitutive models,the Park model,the Mander model and the Saatcioglu model have been adopted in processing the theoretical computation,which results have been compared with that of the test.It can be indicated that the restraining constitutive model of the common concrete is not applicable to the computation of restraining recycled concrete.Through the simulating analysis towards the test data,the computational formula towards the peak stress,peak strain and the ultimate strain of circular restraining recycled concrete component under various mix ratio can be deduced,which the constitutive model that applies to circular restraining recycled concrete component can be proposed base on the results achieved before.