Experimental Study On Axial Compression Of Aluminum Alloy Reinforced Square Wood Column

Chinese wood-frame architecture contains the unique historical and humanistic information of the Chinese nation,and is a crystallization of science and art.Since the 21st century,the concept of low-carbon environmental protection and green building has gained popularity,and wood as a renewable material to meet the demand of environmental protection and green concept,modern wood structure building system has flourished.In coastal and rivers and lakes,etc.,its high temperature,high humidity,high salt spray and other harsh natural conditions have seriously reduced the service life of wood structures.In response to the needs of wood structures in humid environments in terms of bearing capacity,durability,and environmental protection,this thesis proposes a new reinforcement method of aluminum alloy reinforced square wood columns,using a combination of experimental research and theoretical analysis to conduct an in-depth study of the mechanical properties of the reinforced members.A total of 63 specimens were designed for 18 working conditions,and the test variables were wood column cross-sectional size,aluminum alloy tube wall thickness,water-cement ratio of plain cement paste,number of layers of CFRP wrapped wood,end restraint,aluminum-wood contact,and wood column shape.For the mechanical properties of this combined structure,the main research contents and conclusions are as follows:(1)The aluminum reinforced square wood column is mainly damaged by end flexure,and the specimen is mainly damaged by middle flexure after the end restraint is applied.The load-displacement curve is divided into four stages:elastic stage,elastoplastic stage,descending stage and leveling stage,and the load-strain curve is divided into three stages:elastic stage,elasto-plastic stage and descending stage.The peak displacement of all working conditions is between 2mm～3mm,and it still has high bearing capacity and good deformation performance after reaching the peak.During the compression process,the wooden column is effectively restrained by the aluminum alloy tube,and the core wooden column is in a three-way force state,with good mechanical performance as a whole working together.(2)After reinforced by aluminum alloy,the bearing capacity,initial stiffness,ductility and energy dissipation capacity of the square wooden column are well improved.The bearing capacity was improved by 115%～341%after decreasing the size of wood column,increasing the wall thickness,applying upper end restraint and both ends restraint,increasing the strength of plain cement paste and increasing the number of layers of CFRP wrapped wood;the initial stiffness was improved by 124%～326%after decreasing the size of wood column,increasing the wall thickness,applying both ends restraint,increasing the strength of plain cement paste and increasing the number of layers of CFRP wrapped wood;the initial stiffness was improved by 124%～326%after increasing the size of wood column,increasing the wall thickness,applying lower end restraint and increasing the number of CFRP wrapped wood,The ductility increased by 19%～111%after increasing the size of wooden column,increasing the wall thickness,applying lower end restraint and increasing the number of CFRP wrapped wood layers;the energy consumption increased by 250%～1889%after decreasing the size of wooden column,increasing the wall thickness,applying both ends restraint,increasing the strength of plain cement paste and increasing the number of CFRP wrapped wood layers.Among them,the wall thickness of aluminum alloy tube has the most significant effect on the reinforcement effect.(3)With reference to relevant theoretical studies,the formula for calculating the bearing capacity of aluminum alloy reinforced square wood columns was proposed according to the superposition theory.Through the fitting analysis of the test data,it was concluded that the cross-sectional area and strength of the plain cement paste were important factors of the error between the calculated and test values,and the discount factor of the plain cement paste was obtained by fitting and substituted into the formula.The mean value and mean square error of calculation are 5.8%and 0.018 respectively,which are in good agreement with the axial compression test of aluminum reinforced square wood column and provide reference for engineering practice.