Axial Compression Performance Of BFRP Reinforcement Sea Sand Recycled Aggregate Concrete Columns

With the acceleration of urbanization and industrialization,the production and stock of construction waste in China have increased significantly,How to effectively control construction waste has become a major problem in China.In addition,China’s natural resources have become increasingly scarce.For the sake of environmental protection and safety,China has gradually implemented the policy of restricting the exploitation of river sand,resulting in a very limited supply of river sand,resulting in a sharp rise in the price of river sand,greatly increasing the project cost and restricting the development of China’s economy society.In the face of the shortage of natural resources and the siege of construction waste,the preparation of sea-sand recycled aggregate concrete(SRAC)with sea sand and recycled aggregate is undoubtedly a hot spot in the future research.At the same time,in order to avoid the corrosion of steel bars caused by the application of sea sand,BFRP reinforcement is used to replace ordinary bars to prepare BFRP reinforcement sea sand recycled aggregate concrete(BFRP-SRAC)columns in this paper.At present,there are many studies on sea sand,recycled aggregate and FRP materials at home and abroad,but most of these studies are aimed at the material level,and most of them are single factor studies.Few people combine the three,which seriously restricts its popularization and application in practical engineering.Therefore,this paper studies the mechanical properties of sea sand recycled concrete and the axial compression properties of BFRP reinforcement sea sand recycled concrete columns.The main research contents are as follows:(1)Study on physical properties of raw materials composed of SRAC and mechanical properties of BFRP reinforcement: In this paper,the physical properties of recycled aggregate and sea sand are studied,including the bulk density and crushing index of recycled aggregate,and the mechanical properties of BFRP reinforcement are studied.(2)Study on compressive properties of SRAC: In this paper,three groups of cube and cylinder compressive strength tests are carried out.The results show that with the replacement rate of recycled aggregate increasing from 0% to 100%,the compressive strength of SRAC cube and cylinder decrease by 12.58% and 13.37%respectively.(3)Experimental study on axial compression performance of BFRP-SRAC column: In this paper,the axial compression tests of 42 BFRP-SRAC columns are carried out.The results show that the failure modes of BFRP-SRAC columns are different when the spacing of spiral stirrups is different.The smaller the spacing of spiral stirrups,the better the ductility and bearing capacity of BFRP-SRAC columns;The greater the ratio of longitudinal reinforcement,the greater the bearing capacity of the specimen,but the effect of the ratio of longitudinal reinforcement on the ductility of concrete columns is not obvious;The greater the replacement rate of recycled aggregate,the smaller the bearing capacity of the specimen.On the whole,the ductility of SRAC specimens is slightly better than that of SNAC specimens.(4)Study on peak strength model,peak strain model and constitutive relationship model of SRAC confined by BFRP reinforcement: Based on the study of the classical constitutive relationship model,considering the replacement rate of recycled aggregate,the reinforcement ratio of longitudinal reinforcement and the spacing of spiral stirrups,this paper puts forward the constitutive relationship model suitable for SRAC confined by BFRP reinforcement.(5)ABAQUS finite element analysis of axial compression performance of BFRP-SRAC columns: The specimen is simulated and analyzed by ABAQUS,and the failure process,shape,ultimate bearing capacity,peak strain and simulation curve of the specimen are compared with the actual test.