| Reinforced concrete column-steel beam composite structure,referred to as RCS composite structure,its beams and columns adopt different materials,which fully exerts the advantages of good concrete compression performance and high steel strength,and has rationality and economy in material selection.The RCS composite structure is the development trend of high-rise building and large span building in the future.The RCS composite joint is a key force-transmitting component of the composite structure.At present,there are few researches and applications on the RCS composite joint in China,and there is still insufficient understanding of its working performance,and there is no specific code.Therefore,it is necessary to expand the research on the RCS composite joint.In this paper,the static behavior of the plug-in RCS composite joint is studied by a combination of experimental research and finite element simulation.The main research methods,research contents and conclusions are as follows:(1)According to the plug-in RCS composite joint in The World Hakka Entrepreneurs Center in Meizhou,a joint with end plates was designed and its static performance was studied through experiments.The results showed that: During the test,the steel beam is anchored well,and no pull-out failure occurs.The joint failure begins when the flange of the steel beam of the extension section is subjected to compression and yielding.The column reinforcement does not yield during the loading process,which satisfies the requirements of “strong column and weak beam,strong joint and weak component”.It is a ductile failure,and the ductility coefficient is greater than 4,which is higher than the general reinforced concrete structure.According to the Eurocode3,the joint is determined to be a semi-rigid joint.(2)The finite element software ABAQUS is used to simulate the test joints,and the reliability of the finite element analysis is verified by comparison with the test results.The load-displacement curve,the bending moment-turn curve,and the yielding order of the member are basically the same as the test results.The finite element simulation method adopted in this paper can accurately simulate the stress of the RCS composite joint.This finite element simulation method can be used to study such problems.(3)Six factors affecting the performance of RCS composite joints are studied using the validated finite element simulation method.Through research,it is found that increasing the axial compression ratio within a certain range,the steel beam insertion length,the ratio of the beam-column section width and the concrete grade can increase the strength and stiffness of the RCS composite joint,however,the thickness of end plate has little effect on the joint behavior,and the best value of each parameter is given.Four kinds of joint construction,such as expanding the end plate,adding vertical steel column,adding U-shaped anchor ribs and adding welding studs,can improve the joint strength and rigidity to different degrees,and the effect of adding welding studs construction is the best.(4)According to the research results of influencing factors,using the best values of each parameter,a RCS composite joint with good mechanical behavior,simple structure and easy construction is determined.Adopting the extended end plate and the welding stud structure,the steel beam insertion length takes 3/4 of the section width of the column,the ratio of the beam-column section width is 7/20,and the yield strength is 44.1% higher than the basic joint,and the initial slope of the dimensionless bending moment-turn curve is 48.8% higher than the basic joint. |
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