Study On Axial Compression Performance Of Concrete Filled Aluminum Alloy Tube Columns After Being Exposed To Freezing And Thawing

The aluminum alloy pipe concrete has the features of light weight,strong corrosion resistance,good low temperature performance and beautiful appearance,so the aluminum alloy pipe concrete structure has a high research value.So far,Some scholars have studied the aluminum alloy pipe concrete members,but most of them are reflected in the axial compression bearing capacity,bending stability and fatigue resistance of the members at room temperature.However,compared with commonly used metal pipe concrete(steel pipe concrete,stainless steel pipe concrete)components,the thermal expansion coefficient of aluminum alloy pipe material is approximately twice the thermal expansion coefficient of the concrete material.This article serves that as a research background,the effect of freezing and thawing cycles on the interfacial bond strength of aluminum alloy pipe concrete columns and the number of different freeze-thaw cycles on the axial compression behavior of concrete columns with different aspect ratios were investigated.The applicability of the calculation formula of the commonly used metal pipe concrete bearing capacity to the aluminum alloy pipe concrete member was verified.On this basis,the freezing and thawing cycle reduction factor φ was suggested to modify the aluminum alloy pipe concrete bearing capacity formula,and the test results and corrections were used.The comparison of the bearing capacity calculation results shows that the results are in good agreement.The main work of this article is as follows:(1)Gathering data Familiarize yourself with the antifreeze performance of the two materials,read the design specifications of the relevant design specifications,design the temperature curve according to the freeze-thaw cycle specifications,and design a test plan based on the research content.(2)9 aluminum alloy pipe concrete long columns,9 aluminum alloy pipe concrete short columns,and 9 aluminum alloy pipe concrete short columns pushed away from the test piece and some auxiliary test pieces were cast.All the test pieces were divided into three groups.Two sets of freeze-thaw cycle tests were used to collect the strain gauge readings of different test points during the test.The test data was used to analyze the effect of freeze-thaw cycles on the interface bonding performance of the aluminum alloy pipe concrete.(3)Axial compression tests were conducted on three sets of aluminum alloy pipe concrete columns subjected to different cycles of freeze-thaw cycles to study the changes in the behavior and failure modes of the post-freezing and thaw cycles.The aluminum alloy pipe concrete short column was pushed away from the test piece to study the effect of freezing and thawing cycles on the interface bonding strength and critical shear stress of the aluminum alloy pipe concrete.(4)The finite element software was used to simulate the axial compression test process,failure phenomena and ultimate bearing capacity of the aluminum alloy pipe concrete column,and the correctness and feasibility of the FEM software calculation was verified.(5)Through the analysis of test data,the freeze-thaw cycle reduction factor φ is suggested and the aluminum alloy pipe concrete bearing capacity formula is revised.The correctness of the formula for the bearing capacity of the modified aluminum alloy pipe concrete column is verified by the test data.(6)According to the finite element calculation results,the coefficient of stability coefficient of the long column of aluminum alloy pipe concrete columns is recommended.The formula for the ultimate bearing capacity of the long columns of aluminum alloy pipes after freeze-thaw cycle is obtained,and verify the correctness of this formula.