Design And Finite Element Simulation Of Modular Concrete Frame Structure Substation

In order to actively respond to the national policy,the State Grid Corporation of China put forward the requirements for the construction of standard distribution smart substations with "standardized design,factory processing and assembly construction",which promotes the development of power engineering construction in the direction of green,low-carbon and environmental protection.Prefabricated buildings are divided into bar element,boardelement and-modular building system.Among them,modular building has many advantages such as higher building quality and faster construction speed,which can greatly shorten the construction cycle of prefabricated building and reduce the workload on site,thus realizing highly assembled and fast construction of substations.Therefore,this paper takes the modular substation as the research object,and gives the specification and size of the module units in each room of the substation based on data statistics.Using Abaqus,the finite element simulation of the proposed module connection nodes is carried out and the restoring force model is given.The main research content of this paper are as follows:(1)The size data of the typical design schemes of different voltage levels of substations are summarized.Considering the limiting conditions and hoisting on the size of the module,the general size specifications of the module are slightly adjusted without affecting the use function.Module size specifications ands typical module assembly scheme suitable for outdoor substations with different voltage levels are given.(2)The commonly used prefabricated joints are statistically summarized,which are analyzed from four aspects of bearing capacity,ductility,energy dissipation capacity and difficulty of construction and installation.and the prestressed connection mode is selected as the connection between adjacent modules.In order to enhance the seismic performance of joints and reduce the difficulty of installation,mortise and tenon connections and angle steel are adopted to optimize prestressed joints.(3)According to the arrangement of prestressed tendons,a new unbonded prestressed frame model,a hybrid prestressed frame model,a unbonded prestressed frame model without angle and a cast-in-place model are established,and their numerical simulations were carried out using Abaqus.The simulation results show that the energy dissipation capacity of the unbonded prestressed frame model is relatively poor,but its residual deformation is small and the concrete damage is small,and it has good self-recovery capability;the setting of nodal angle steel can improve the structural bearing capacity and energy dissipation capacity,while the application of unbonded prestressing tendons can help slow down the stiffness degradation rate of the structure,thus improving the seismic performance of the structure.(4)Taking the new unbonded prestressed frame model as the research object,10 working conditions are designed to simulate the seismic performance of the frame model according to the difference of concrete strength grade,prestress magnitude,angle steel strength grade and thicknessand axial compression ratio.The simulation results show that the magnitude of prestress and axial pressure have great influence on the elastic-plastic performance of the structure,and the increase of prestress and axial pressure will greatly increase the initial stiffness,ultimate bearing capacity and energy dissipation capacity of the structure.The increase of axial pressure will reduce the ductility coefficient of the structure,while the change of prestress has little influence on the ductility coefficient.(5)Based on the simulation data of unbonded prestressed frame model under 10 working conditions,the stiffness degradation formula and hysteretic rules are obtained by standardizing the skeleton curve and stiffness degradation data.Furthermore,a restoring force model suitable for the new prestressed frame structure is established.Through the comparison of the restoring force model and the finite element simulation results under six typical working conditions,it can be concluded that the restoring force model proposed in this paper has high accuracy and can better reflect the seismic performance of the new frame structure.