| Assembled structures once withdrew from the historical arena because of their poor seismic performance.However,with the development of science and technology,It is found that the unbonded prestressed concrete assembled structure adopting Japanese "pressing method" has better integrity and continuity,which can improve the reliability of the joint.Moreover,this kind of structures has the advantages of energy saving,environmental protection,high-quality and high-speed construction.At the same time,due to the less residual deformation of the structure and the stronger self-resetting function after the earthquake,it is beneficial to the post-earthquake repair work.Therefore,these structures are worth of further study.At present,there are still relatively few research on such structures in China.In current research,the energy dissipation of nodes is low,but little research has been done on how to improve energy consumption.In addition,the whole process response of the whole structure under earthquake has not been fully studied.And there is no specification for how to design such structures.In this paper,using finite element software ABAQUS,the low-cycle cyclic load simulation and elastoplastic time-history analysis of the joints and the whole structure of this kind of structure are carried out respectively.Then the seismic performance of this kind of structure is comprehensively analyzed.Finally,a design method is proposed to design this kind of structure.The specific contents are as follows:are extremely easy to assemble and will promote the industrial development of the building.Therefore,the seismic performance analysis and design method of this kind of structure are proposed.The specific contents are as follows:1.To overcome the problem of small energy dissipation for precast unbonded prestressed concrete joints,a precast unbonded prestressed concrete joints with ductile rods was proposed in this paper.The ductile rod is made of a low yield point steel and added in precast unbonded prestressed concrete joint to improve energy dissipation ability.In order to study the seismic performance of the joints,we used FEM to analyze it.Firstly,Dongyan Wang’s experiment of Beijing university of technology is selected to verify the model.Then the seismic performance and energy dissipation of the joints with and without ductile rod were determined and comparad.Finally,how different parameters impact the seismic performance of the joints are determined,such as single rod diameter,single row rod numbers,arrangement position and prestressing degree.2.Select a unbonded prestressed concrete fabricated frame structure with ductile rods and the same frame structure without ductile rods for pseudo-dynamic analysis.Through the analysis of the relative displacement time history curve of the top story,the maximum displacement angle between stories,the base shear force,the overall seismic performance and the whole seismic response of this kind of structure are determined.3.Introduce the relative rotational stiffness ratio of the joint to determine the semi-rigidity of the joint,and derive the relative rotational stiffness matrix of the joint and the angular displacement equation of the semi-rigid beam element according to the structural mechanics method.The relative rotational stiffness ratio of the joints is taken as the criterion to classify the nodes and obtain the semi-rigid interval of the nodes.Established an internal force calculation method of the unbonded prestressed concrete assembled structure under vertical load.4.Finally,according to the relative rotational stiffness of the joint,a new calculation method is proposed to design the unbonded prestressed concrete assembly structure,and an example calculation is carried out.The new calculation method is bending moment amplitude modulation according to the relative rotational stiffness ratio of the nodes rather than simple internal force amplitude modulation,which is more consistent with the characteristics of different structures. |
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