| The prefabricated assembly is of great significance to the construction industry to achieve sustainable development,to build a resource-saving and environment-friendly society.The prefabricated assembly type not only has the advantages of simple production process,low environmental pollution,cost saving,and shortened cons truction period,but also can make up for the loss of my country’s demographic dividend and bring a new climax to the development of my country’s construction industry.According to China’s national economic and social development plan,my country will vig orously develop prefabricated buildings in the future to achieve the goal of "building industrialization and housing industrialization".In addition,the prefabricated concrete structure is a green construction method vigorously promoted by the country,an d the key to ensure that the prefabricated concrete structure has good seismic performance is the processing of the prefabricated component nodes.The current grout sleeve splicing of rebars is the conventional connection method for the prefabricated struc ture.Among them,grout sleeve splicing of rebars is less restricted by the natural environment,simple to operate,and has a wide range of applications.It has scientific research significance and engineering application value for promoting the sustainabl e development of our country.For this reason,this article takes the grouting sleeve made of 45# seamless steel pipe and ductile iron Q600 commonly used in engineering as the research object,and uses a combination of theoretical analysis,experimental research and numerical simulation to explore the connection of this type of reinforced grouting sleeve Seismic performance aims to provide part of the theoretical basis and test data for the application of prefabricated component connections in prefabricated buildings.The main research contents and conclusions of this experiment are as follows:(1)The uniaxial tensile properties of the specimens connected by the grout sleeve splicing of rebar have been studied.In this study,24 grouting sleeve steel connect ion test pieces were made by using sleeves made of 45# seamless steel pipe and ductile iron Q600.Firstly,the force mechanism,failure mode and surface restraint mechanism of the grouting sleeve steel bars are experimentally studied;secondly,the specime ns made of grouting sleeves made of the same material and different specifications and the same specifications and different materials are co MPared and analyzed.The research results show that: 24 grouting sleeve steel bars are connected by steel bar fract ure failure,and the grouting material in the sleeve is only partially crushed at both ends and tapered off or cracked,and there is no obvious sign of damage in the rest of the range.The ultimate bond bearing capacity of the joint of the grouting sleeve steel connection test piece is greater than the ultimate tensile strength of the steel bar.All test pieces meet the Class I joints specified in the specification.(2)The research on the hysteretic performance of the grouting sleeve steel connection test piece was carried out.Firstly,the uniaxial tensile statics test verified that the grouting sleeve steel bar connection satisfies the mechanical properties of the joint.Then prepare 24 grouting sleeve steel connection test pieces and 24 equal slenderness ratio steel bar test pieces that are the same as the research object of the uniaxial tensile test,and test the preparation of grouting sleeves of the same material with different specifications and the same specifications with different materials.The ant i-seismic performance of the parts,and discuss the hysteretic performance and failure mode of the grouting sleeve steel connection,co MPared with the equal length and slenderness ratio steel,reveal the advantages and disadvantages of the grouting sleeve steel connection under the action of seismic load.The results of the study show that the skeleton curves of the specimens made of the two materials basically coincide,the ultimate bearing capacity of the specimens with the same diameter is almost the sam e,and the material has no obvious effect on its bearing capacity.The energy consumption curves of grouting sleeve steel bar specimens with steel bar diameters of 12 and 16 almost coincide,but as the diameter of the connecting steel bar increases,the energy consumption,plastic deformation capacity and seismic performance of the grouting sleeve prepared from the45# seamless steel pipe are better The grouting sleeve is made of nodular cast iron Q600.The energy dissipation capacity,plastic deformation capacity and seismic performance of equal slenderness ratio steel bars will be better than grouting sleeve steel connection joints.(3)Through co MParative analysis of the failure mode of the grouting sleeve steel bar connection joints under different loading methods,the results show that the grouting sleeve steel bar connection of 45# steel material is under uniaxial tensile load,and the grout only has local compression at both ends.It broke and fell off in a cone shape,and there were no cracks in the remaining parts.However,under the action of low-cycle repeated tension and compression loads,the grouting material produced cracks on the contact surface of the annular rib,the anchor end of the steel bar and the grouting material.Nodular cast iron grouting sleeve steel bars are connected under unidirectional tensile load and low-cycle repeated tensile and compressive loads.The grout is only partially crushed at the non-blocking port and tapered off,and the other end is caused by the designed blocking When the thrust effect is obvious,only small cracks or even no obvious phenomenon are generated in the grouting material.The local damage of the grouting material at the two ports of the specimen under uniaxial tensile load is greater than that of the specimen under low-cycle repeated tension and compression,but under the action of low-cycle repeated tension and compression,the damage range of the grout is larger.Therefore,low-cycle repeated loads will cause the joints to fail prematurely due to extensive cracking of the grouting material.(4)The nonlinear numerical simulation of the seismic behavior of grouted sleeve steel connection members was carried out.Combining uniaxial tension and low-cycle repeated tension and compression tests,a precise finite element model of the grouting sleeve steel connection was established based on the ABAQUS software,and the mechanical behavior of the grouting sleeve steel connection members under the action of low-cycle repeated tension and compression loads was carried out.Parameter analysis.The research results show that the load-displacement curve of the numerical simulation specimen under uniaxial tension and low-cycle repeated tension and compression loads is basically in line with the test results,and the Mi ses stress distribution of the model component is basically consistent with the failure of the specimen,which proves limited The accuracy and reliability of the meta-model.Under unidirectional tensile load,when the thickness of 45# steel sleeve is 2mm thick,the joint performance of the test piece cannot be satisfied.When the steel bar is still in the yielding stage,the sleeve has reached the ultimate tensile strength.However,the ductile iron Q600 sleeve yields only when the thickness of the ductile iron sleeve is 3mm and the reinforcement is in the strengthening stage.This shows that the restraint effect of the ductile iron Q600 sleeve has a lot of surplus.Therefore,in actual engineering,it can be reduced by reducing the sleeve.The thickness of the barrel achieves the win-win goal of meeting structural performance and cost saving,and accelerates the development of prefabricated buildings. |
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