Quasi-static Experimental Study And Finite Element Analysis On Compound Concrete Composite Shear Wall Made Of Demolished Concrete Lumps And Self-compacting Concrete

Demolished concrete lumps concrete is an effective way in recycling demolished concrete.Our research group conducted a preliminary exploration of the basic mechanical properties and disaster resistance of demolished concrete lumps concrete and its components.On this basis,in order to improve the construction quality and efficiency of demolished concrete lumps concrete,this paper conducted an experimental study on the direct shear performance of compound concrete made of demolished concrete lumps and self-compacting concrete.At the same time,in order to apply the demolished concrete lumps concrete to the composite shear wall structure,this paper combines the steel pipe concrete edge constraint,self-compacting concrete and demolished concrete lumps,and proposes a composite shear wall made of demolished concrete lumps(DCLs)and self-compacting concrete(SCC).And the quasi-static test and finite element analysis of the composite shear wall are carried out.The main achievements and conclusions include that:In this paper,the prisms made of normal strength demolished concrete lumps(DCLs)and high-strength fresh self-compacting concrete(SCC)were tested under two-sided direct shear loadings and uniaxially compressive loadings..The influences of the replacement ratio of DCLs and the characteristic size of DCLs on the shear strength of specimens have been investigated.,and the relationship between the test value of direct shear strength and the calculated value of compressive strength was obtained.The results show that when the strength of SCC is much higher than that of demolished concrete,the incorporation of demolished concrete lumps will degrade the direct shear strength of the specimens;the influence of block characteristic size on the direct shear strength and compressive strength of self-compacting recycled lumps concrete can be neglected approximately;a formula for predicting the direct shear strength of self-compacting recycled lumps concrete is presented;the ratio of direct shear strength to compressive strength of concrete made of DCLs and SCC remains unchanged with the change of replacement rate and characteristic size of demolished concrete lumps,and the ratio of shear strength to compressive strength of self-compacting recycled lumps concrete is about 1/10.The quasi-static test of composite shear walls made of DCLs and SCC is carried out,and the effects of the replacement ratio of DCLs,axial load ratio and the square steel tube thickness of edge restrained end column on the bearing capacity,the hysteretic curve,the skeleton curve,the stiffness degradation curve and the energy consumption capacity of composite shear wall are revealed.The results show that when the difference between thecompressive strength of demolished concrete and that of new concrete is small,the mixing of demolished concrete lumps has little effect on the seismic performance of composite shear wall;the failure displacement angle of the composite shear wall meets the requirements of the code,and the composite shear wall has great variability after yielding and good ductility;the increase of axial load ratio will have a significant impact on the seismic performance of composite shear wall;the influences of the mixing of DCLs on the energy dissipation capacity and initial lateral stiffness of composite shear walls are limited,while the increase of square steel tube thickness and axial load ratio in a certain range can improve the energy dissipation capacity and initial lateral stiffness.the prediction formula of horizontal bearing capacity of composite shear wall is put forward.By using ABAQUS software,the calculation model of composite shear wall is established,and the influences of the replacement ratio of DCLs,axial load ratio,the square steel tube thickness of edge restrained end column and longitudinal reinforcement ratio of prefabricated wall panel on the horizontal bearing capacity of composite shear wall are analyzed.The results show that the calculation curve of horizontal force and horizontal displacement of composite shear wall under monotonic loading is in good agreement with the test skeleton curve under reciprocating loading,but the difference between the calculation curve and the test skeleton curve is obvious,and the softening behavior of this kind of structure can not be well reproduced;the change of the replacement ratio of DCLs and the longitudinal reinforcement ratio of prefabricated wall panel has little effect on the horizontal bearing capacity and initial stiffness of composite shear wall;increasingaxial load ratio and the square steel tube thickness of edge restrained end column can improve the horizontal bearing capacity of composite shear wall,but the ductility is reduced.