| The prefabricated steel structure building has the advantages of small self-weight,high ductility,recycling,and industrial production.Under the premise of effectively ensuring the construction quality,it can greatly reduce construction pollution,improve construction speed and construction efficiency,and reduce resource consumption.It is a green sustainable development architectural form and has good development prospects.Prefabricated steel structure buildings mainly rely on assembled beam-column joints to realize assembly construction.There are significant differences in mechanical properties and assemblability of different beam-column joints.A new type of inner sleeve assembled square steel tube column and H-shaped steel beam connection joint is proposed.The splicing position of the upper and lower columns is moved up to the top of the beam flange,so as to avoid the use of unilateral bolts or long bolts for column splicing within the height range of the beam.When the bolt is connected,it is not necessary to open a hand hole at the column wall for repair welding,which is convenient for construction and enhances the reliability of the joint connection.It ensures the reliable force transmission of the joint domain,and can realize the factory production and on-site assembly construction of the beam-column connection components,and has good assembly performance.In order to further study the mechanical properties of the new inner sleeve assembled joint and the application of the new joint frame,the following studies were carried out :Based on the component method recommended by the Eurocode 3,the inner sleeve assembly joint is divided into several basic components.The stiffness calculation formula of each basic component of the joint is derived by using the Card ’s second theorem.Finally,the initial stiffness calculation formula of the joint is derived.The calculation formula of the initial stiffness of the joint is verified by the finite element results of the existing research.The results show that the initial rotational stiffness of the two joints is in good agreement and the results are reliable.The simplified model of the node spring component is established,and the simplified finite element model of the spring component of 7 groups of nodes is established by ANSYS finite element software for static and quasi-static analysis.The simplified finite element model of the spring component is verified by the existing solid finite element results.The results show that the simplified finite element model of the spring component of the joint is in good agreement with the calculation results of the solid model,whether under unidirectional loading or cyclic loading.The load-displacement curves of the joints are consistent and in good agreement.The errors of initial rotational stiffness,yield load,ultimate load and failure load are within ± 10 %.Because the simplified model of the joint spring component greatly improves the calculation efficiency,a large number of simplified finite element models of the spring component of the inner sleeve assembly joint spring component with refined parameters are established for quasi-static analysis.The influence of the simultaneous change of the two parameters of the inner sleeve thickness and the end plate thickness on the initial stiffness,energy dissipation capacity,yield bearing capacity and ductility performance of the joint is studied.The results show that when the thickness of the inner sleeve and the thickness of the end plate increase,the initial stiffness,energy dissipation capacity,yield bearing capacity and ductility performance of the joint are improved to varying degrees,but the increase amplitude decreases with the increase of the thickness of the component.When the thickness of the two changes between 12 mm ～ 16 mm,the performance of the joint increases significantly with the increase of the thickness,but the effect of increasing the thickness is not obvious.When the thickness is too large(more than 17 mm or 18mm),the performance of the joint begins to decrease to varying degrees.Therefore,it is suggested that the thickness of the inner sleeve and the thickness of the end plate should be kept in the range of 2mm ～ 4mm greater than the thickness of the column wall.The simplified finite element model of the steel frame with inner sleeve assembled joints is established by using the spring component of the joint to simplify the finite element model.Two natural waves and one artificial wave are selected for dynamic time history analysis.The differences between the frame with inner sleeve assembled joints and the frame with ordinary welded joints in modal parameters,vertex displacement response,column base shear response,maximum interlayer displacement angle of each layer and stress distribution of beam-column joints are compared to study the dynamic performance and seismic performance of the frame with inner sleeve assembled joints under frequent and rare earthquakes.The analysis shows that under the action of frequent earthquakes and rare earthquakes,the maximum inter-story displacement angle of each layer of the inner sleeve assembled joint frame meets the limit requirements of the specification,but its lateral stiffness is less than that of the ordinary joint frame.The column bottom shear force of the frame can be reduced when the inner sleeve assembled joint is adopted.The stress of the column wall of the inner sleeve assembled joint frame is much smaller than that of the beam end.The stress distribution of the beam-column joint is reasonable,which conforms to the design concept of " strong column weak beam,strong joint weak component." At the same time,due to the outward movement of the plastic hinge of the inner sleeve assembled joint,the brittle fracture at the weld of the beam-column joint in the frame can be effectively avoided.The research in this paper shows that the inner sleeve assembled joints have good seismic performance,and the proposed initial stiffness calculation formula and design suggestions can provide basic data for the application of the joints.The maximum inter-story displacement angle of the steel frame with inner sleeve assembled joints under frequent earthquakes and rare earthquakes meets the requirements of the specification limits.The bottom shear force of the steel frame with inner sleeve assembled joints is smaller,which realizes the outward movement of the plastic hinge,avoids the brittle fracture at the weld of the beam-column joints,and has better dynamic performance.The research conclusions can provide reference for the popularization and application of steel frame with inner sleeve assembled joints. |
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