Study On Seismic Performance Of Prestressed Frame Joints With X Type

From the "safety" and "durability" of the building structure,the design of the structure must be considered at the beginning of its seismic performance,the building should have the function of protecting the personal safety of users,property safety and living environment,and in the event of an earthquake should do In case of an earthquake,the building should be able to achieve the function of "no damage in a small earthquake,repairable in a medium earthquake,and not collapse in a large earthquake",and have sufficient seismic performance.As an important part of the frame,the nodes have the role of transmitting internal forces and distributing loads,and are also the parts of the building that ensure the safety and stability of the structure,while there are many hoops in the core area of the nodes,and the construction is also particularly complicated.In the usual seismic design,the designer usually adopts the design quasi-side of "strong shear and weak bending,strong nodes and weak members" to design the building with sufficient seismic performance.In order to avoid shear failure of the nodes or shear damage at the beam or column ends before the yielding of the tensile reinforcement,and to facilitate the construction of the nodal cores,we designed an X-shaped prefabricated nodal structure.We designed a new node with X-shaped prestressed reinforcement.We have designed a new type of stiffening joint with X-type prestressed steel bars.When an earthquake occurs,plastic hinges should be avoided in the core area of the joint,and the number of stirrups in the core area of the joint should be reduced.The main elements are as follows:(1)The damage form of beam-column nodes,the damage mechanism,the transmission mechanism in the core area and the factors influencing the seismic performance of the node core area are described.The beam-column nodes used in the simulations are described to lay the theoretical foundation for the following study.2)An exhaustive description of the process of model establishment,a detailed description of the establishment of unbonded prestressing reinforcement,and the process of applying prestressing by the cooling method.3)Through ABAQUS finite element simulation software,25 ordinary nodes and unbonded prestressed reinforced nodes were established respectively,and the differences in seismic performance were compared by changing different influencing factors: the number and size of prestressing,the number of hoop bars configured in the node core area and ordinary nodes.The results show that for ordinary nodes the damage is generally in the core region of the node,while for prestressed strengthened nodes the members are at the beam end,plastic hinge formation and beam end.The hysteresis curves of prestressed strengthened nodes are fuller,the maximum bearing capacity is improved,the ultimate load is improved,the initial stiffness is improved,and the decline is smoother,and the energy dissipation capacity and ductility performance are improved.For the size of the prestressing reinforcement has little effect on the ultimate load carrying capacity and maximum load carrying of the nodal member,because the damage is at the beam end and its load carrying capacity is determined by the concrete and reinforcement at the beam end...