Study On Mechanical Performance Of Modular Steel Structure Building Connection Joints

The modular steel structure building hasmany advantages,such as modular design,factory production and assembly construction.It is a highly integrated fabricated building form.In practice,the construction site is only needs to connect adjacent modules to form a whole building,except for equipment and pipes.Therefore,the mechanical performance of connection joint of adjacent modules is very important to ensure the integrity of the building structure.Due to those disadvantages of the current connectionjoints between adjacentmodules of modular steel structure building,a novel connectionjoint has been taken as researchin this paper,the relative influence factors of the mechanical performance of modular steel structure building connection joint has been studied,such as the connection joints position,the direction of load,and connection rods between columns on joint.In summary,the main work is as follows:(1)The four edge joints and four middle jointsof the modular steel structure building were designed for unidirectional static loading test.According to the test phenomenon and data analysis,the relative results can be obtained as follows:(1)the final failure mode of the novel connection joint is the tearing of the edge of the steel plate weld at the loading end beam-column connection position;(2)the joint measured bearing capacity of the connection joint with same form connection rods between the joint columns is good agreement with the connection joint withoutthose connection rods,and the relative difference between the two specimenis within 5%,hence,it is recommended to cancel the connection rods between the joint columns;(3)when the rotational angleof connection joint is 1/250,the design value of the bending capacity of the connectionjoint are 29.27kN·m(JD4-X),22.24kN·m(JD4-Y),77.71kN·m(JD8-X),82.90kN·m(JD8-Y),respectively;(4)the force state of single-layerbeam and column in double-layer beams and columns specimen is independent,and the overall coordinated force state is not achieved in double-layer beams and columns specimen,hence,the bearing capacity of double-layer beams and columns specimenis the sum of the bearing capacity of thetwo single-layer beam and column.(2)The solid elements are selected for numericalsimulation in ABAQUS,and the welding parts are mergedprocessingin finite element model.The face-to-face contact is used to theinteractionof the finite element models,in addition,the boundary conditions of the finite element model are good agreement with the test specimens.The numerical simulationresults of the 8 specimen models can be obtained as follows:(1)the failure modes of finite element modelare good agreement with the test specimens,such as the overall failure mode,the specimen fixed-end failure mode,the beam-end failure mode,and the column-end failure mode(2)load-displacement curve: the calculated bearing capacity is close to the test bearing capacity,and the relative error is within 5%;in addition,the calculated elastic stiffness of the finite element modelsare greater than the test specimens and the relative error is about 5%~15%.The initial defects and weld quality are considered as the major reasonin the difference between finite element models and test specimens in this paper.(3)According to the principle of equivalent stiffness,theMidas Gen software is used to simplify the connection joint model.Beams,columns and module connection rods of the connection joint are beam elements in simplified model.The beams and columns are merged processing in the simplified model,and the module connection elements are solid web circular beams with the diameter of 30 mm.Hence,the lateral and longitudinal stiffness reduction factors of the module edgejoint connection element are 0.2 and 0.18,respectively.The lateral and longitudinal stiffness reduction factors of the module middle joint connection element are 0.2 and 0.18,respectively.In addition,the equivalent cross-section diameter can be also used to reduce the stiffness of the connection element when defining the connection element.Therefore,the lateral and longitudinal cross-section diameters of edge joint connection elements in simplified model are 20.0mm and 19.5mm,respectively.And the lateral and longitudinal cross-section diameters of middle joint connection elements in simplified model are 22 mm.In summary,the recommended stiffness reduction factors of the connection element of the edge joint module and middle joint module are 0.18 and 0.3,respectively.In addition,if thebeam connection elementequivalent cross-section simplified model is adopted,the recommended diameters of the connection elementsof the edge joint module and middle joint module are 19.5mm and 22.0mm,respectively.