Study On Mechanical Properties Of Semi-grouting Sleeve Specimens With Construction Defects After High Temperature

With the development of urbanization and the progress of technology,the proportion of assembled building structures is increasing year by year.Compared with traditional cast-in-place concrete structures,assembled buildings have the advantages of high construction accuracy,good economic efficiency and guaranteed product quality.The mechanical properties of steel sleeve grouting connection,as the most widely used nodal connection technology for prefabricated components,affect the safety of the whole structure.As the proportion of buildings in the city increases year by year and the population density continues to increase,the impact of fire on buildings cannot be ignored.In the actual construction process,the steel sleeve grouting connection technology faces problems such as insufficient site conditions and construction personnel skills,which seriously affects the mechanical properties of grouting sleeve specimens.This paper analyzes the mechanical properties of half-grouted sleeve specimens with construction defects after high temperature,based on the "Mechanical properties of fully grouted sleeve connections of assembled concrete structures after fire（1908085ME173）" supported by the Natural Science Foundation of Anhui Province.The main work of this paper is as follows:（1）In this paper,48 sets of semi-grouted sleeve specimens with construction defects（end defects,middle defects,rebar eccentricity defects,middle plus end defects）were designed and fabricated in conjunction with the actual situation,and the specimens were heated at high temperature,raised to the specified temperatures（200°C,300°C,400°C,500°C,600°C）until natural cooling,and then subjected to one-way tensile tests..（2）Combine the damage phenomena of the semi-grouted sleeve specimens after the test at high temperature,compare the load-displacement curve and load-slip curve,and analyze the peak load,end slip,and bond stress of the specimens.（3）Using ABAQUS finite element analysis software to verify the test,numerical simulation of one-way tensile of semi-grouted sleeve specimens with construction defects after high temperature is performed and compared with the load-displacement curves of the actual test for analysis.The results showed that（1）two damage modes mainly occurred in the semi-grouted sleeve specimens in this test,which were reinforcement pull-out damage and reinforcement pull-out damage.（2）The yield strength and tensile strength of the reinforcing steel decreased after high temperature at600℃ to natural cooling,compared with the steel at room temperature,but still can reach more than90% of the strength;the grout was affected by high temperature after 600℃ with the compressive strength reduction coefficient of 0.535 and the flexural strength reduction rate coefficient of 0.31.（3）With the increase of temperature,when the temperature reached 500℃-600℃（3）With the increase of temperature,when the temperature reaches 500℃-600℃,the tensile property of the half-grouted sleeve specimen with full grouting has a greater effect.And when the temperature reaches 300℃-400℃,the defects have a greater effect on the tensile properties of semi-grouted sleeve specimens.（4）Different types of defects have different effects on the mechanical properties of semi-grouted sleeves.The order of the effect of defects on specimens is: end 3d defect > middle 2d defect > middle plus end 2d defect >end 2.5d defect > end 2d defect > end 1d defect > rebar eccentricity defect > full specimen.（5）Numerical simulation results compared with the test,the tensile process and load displacement curve trends are roughly fitted,but there are still some errors.Figure [73] Table [15] Reference [50]...