| Steel tube confined steel reinforced concrete(STSRC)columns have good plasticity and seismic performance,but because the steel tube outside the column is disconnected in the beam-column joint area,when it is applied to beam-column joints,the strength of the joints is relatively weak,therefore,the joint form of this kind of structure needs to be further studied.However,at present,the research on this kind of structure mainly focuses on the behavior of columns,and the research on joints is less.In the previous experiments,the seismic behavior of two circular steel tubed confined H steel reinforced concrete column steel beam frame ring beam joint was studied.In order to make the joint plastic hinge move out and reduce the damage degree of concrete in the joint area,a new type of joint,circular steel tube confined steel reinforced concrete column-dog-bone weakened steel beam joint,is proposed to optimize the joint structure of test specimens.And the seismic performance of the joint is analyzed by ABAQUS6.10 software.The main research work and conclusions are as follows:(1)The three-dimensional model of test specimens was established by ABAQUS6.10 software,and the finite element simulation analysis was carried out.The results of the finite element analysis were in good agreement with the experimental results,which verified the correctness of the modeling method.(2)On the basis of consulting relevant codes,appropriate parameters are selected to weaken the flange of steel beam and analyze the seismic performance of new joints.The results show that the strength,stiffness and ductility of the joint specimens decrease slightly by weakening the flange of the outer steel beam end of the ring beam,but the plastic hinge position of the joint moves out obviously and the strain value of the concrete in the joint area decreases obviously.It shows that weakening the end of the outer steel beam of the ring beam can protect the joint area,make the plastic hinge move out,and better guarantee the "strong joint,weak member".(3)Variable parameter analysis is carried out for the new type of joints,and the effects of flange weakening parameters,beam-column linear stiffness ratio,axial compression ratio of columns and volume stirrup ratio of ring beams on the seismic performance of the joints are clarified.The results show that the axial compression ratio of columns and the linear stiffness ratio of beams to columns have great influence on the seismic performance of the joints,the stirrup ratio of ring girder volume and the flange weakening parameters of steel girder end have little influence on the strength,stiffness,ductility and energy dissipation capacity of the joints.it mainly affects the damage degree of concrete in joint area.The recommended ranges of parameters are also given.(4)According to the results of parameter analysis,the calculation formulas of horizontal bearing capacity,flexural bearing capacity and shear bearing capacity of joint area are put forward,which are applicable in a certain range.The calculation errors of the formulas are less than 5%,and they have certain applicability,which can provide reference for the design,engineering application and further research of such joints. |
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