Analysis On Seismic Performance Of The New Fabricated Cross-shaped Beam-column Joint

In recent years,based on the needs of green building and building industrialization,as a new architectural form with the characteristics of modularity,high efficiency and low pollution,prefabricated building has gradually shown fresh vigor and vitality with the strong support of the state.The steel bar connection in the core area of the joint is of great significance to ensure the overall performance of the prefabricated concrete frame structure.However,at present,the commonly used connection methods such as mechanical connection and grouting sleeve connection still face some problems,such as unwarranted quality,tedious on-site operation,the need for temporary support and so on,which not only increases the cost,but also affects the efficiency.Therefore,it is of great practical significance to develop a new prefabricated beam-column joint with good seismic performance and excellent construction convenience.In order to solve the problems mentioned above,a new type of prefabricated beam-column joint is proposed in this thesis,and its seismic performance is studied by means of test and finite element simulation.The main tasks of this thesis are as follows:(1)Adopting YJK structure design software,this thesis designs a cast-in-place joint specimen and a new type of prefabricated joint specimen under 1/2 reduced-scale according to the calculation results,and then test this two specimens though low-frequency cyclic loading tests.(2)Through sorting out the data collected by the experiment,this thesis compares and analyzes some key seismic performance parameters such as failure pattern,hysteresis loop,skeleton curve,bearing capacity,strength degradation,stiffness degradation,energy dissipation capacity and ductility between the cast-in-place specimen and the new prefabricated specimen.The results of the research show that under the effect of low-frequency cyclic loading,both the cast-in-place joint specimen and the new prefabricated joint specimen show the failure of “beam-hinge mechanism”,but the positions of the failure are different.The new prefabricated joint specimen shows higher bearing capacity and stiffness,and the energy dissipation capacity is the same.Although there is a certain gap of the deformation performance compared with the cast-in-place specimen,the new prefabricated joint specimen also meets the requirements of the standard and shows good seismic performance.(3)The fine finite element models of the cast-in-place specimen and the new prefabricated specimen are established by using ABAQUS finite element software,and the load-displacement curve,failure pattern and material stress nephogram are compared and analyzed,which verify the rationality of the model.On the basis of verifying the effectiveness of the model,the effects of these factors on the structural performance of new prefabricated joints are further analyzed by changing the parameters of axial compression ratio,concrete strength grade in core area,thickness and length of steel sleeve and so on.(4)Based on the results of experiment and finite element analysis,the optimization suggestions of the new prefabricated joint are given.The joint is also compared with the commonly used prefabricated integral frame structure beam-column joints in the aspects of stress performance,economic performance and construction.The results show that the new prefabricated joint connection method proposed in this thesis is faced with great application prospect.