Study On Mechanical Properties Of Fabricated Beam-column Connection Joints Using Inner Sleeve Composite Bolts

Prefabricated steel structure has the characteristics of standardization,seriation and productization,which can meet the requirements of the industrialization development of the residential buildings,and has excellent seismic performance,short construction period and good comprehensive technical and economic indexes.The development of prefabricated steel structure,expansion of prefabricated steel structure market share,will accelerate the process of housing industry,which also is of great significance for China's construction,metallurgy and related industries.There is little doubt that fabricated beam-column connection joint's research and development are one of the important parts of the development of prefabricated steel structure,but the research on its form and properties is still in its infancy in China,therefore,this paper proposed combination form of fabricated beam-column connection joints using inner sleeve composite bolts and it was carried out by theoretical derivation,numerical analysis and experimental research,which is not only a kind of exploration to fabricated beam-column connection joints in our country,but also a useful complement to the semi-rigid design method of the prefabricated steel structure in our country.In this paper,the initial stiffness of fabricated beam-column connection joints using inner sleeve composite bolts was deduced by the classical beam theory of structural mechanics,and gives the initial stiffness formula under the two forms of presence of strengthening rib plate,then analyses the static performance by using the finite element software ANSYS,comparing the initial stiffness of the numerical from the numerical simulation and theoretical derivation value,have achieved good consistency.After that,this paper designed the three specimens of cross-shaped fabricated beam-column connection joints using inner sleeve composite bolts,and to carry out the quasi-static test research,studied its seismic performance.Finally,according to the test specimens,this article carries on the finite element numerical simulation contrast analysis.The results show that:1,Fabricated beam-column connection joints using inner sleeve composite boltsbelongs to the semi-rigid connection,and this paper deduces the joint's initial stiffness formula in considering and not considering strengthening rib plate of calculating accuracy is higher,which can provide reference for the practical application and theory research of this kind of joint.2,The initial stiffness of fabricated beam-column connection joints using inner sleeve composite bolts increase with the increase of the thickness of the inner sleeve,increase slightly with overhanging end plate thickness increases,along with the increase of clearance between the outer wall of the inner sleeve and the column wall decreased significantly,while the strengthening rib has great effect on improving the initial stiffness,and the initial stiffness increased by 24% on average.3,The initial stiffness of fabricated beam-column connection joints using inner sleeve composite bolts show enough bearing capacity,good stiffness and energy dissipation capacity,which proves that it has good seismic performance.Increase the thickness of the inner sleeve can improve the yield capacity and ultimate bearing capacity of joint,greatly reduce the shear deformation of the core region,but also reduce the ductility and increase the degree of joint stiffness degradation.4,Compared with the welded joint,the bolt type joint has better energy dissipation and larger joint stiffness,but the bearing capacity is lower,the shear deformation of the core area of the joint is larger,and because the beam web is not connected with the extended end-plate,shear force within the beam end and bending moment only need for weld of extended end-plate,strengthening rib and cover plate to bear,it require higher weld quality because of brittle fracture.5,In order to meet the needs of practical engineering installation that must be set by the installation clearance has important effects on mechanical properties of the joint,that effects can makes the inner sleeve and the outer column not maintain synergy,make the phenomenon of "rocker phenomenon” between extended end-plate and the column wall is more obvious,increase the slip of through high-strength bolt,and the plastic deformation mostly happen in the column wall and extended end-plate,it is difficult to form a larger range of plastic zone on beam,and by reducing this installation error,the joint which is expected by the design can be obtained failure mode.