| Power transmission and transformation project is an important lifeline project,in which the main transformer equipment plays the role of conversion hub.In the past earthquake disasters,there are a large number of cases of main transformer equipment damage,which not only directly cause huge economic losses,but also bring serious secondary hazards such as fire and power failure.The box of main transformer equipment is often connected with heavy iron core and winding elements through brittle insulating materials.The slender ceramic bushing is extremely sensitive to the low frequency component of ground motion,so it needs to ensure that it is not damaged by earthquake.Therefore,the isolation bearing of main transformer equipment needs not only good isolation efficiency,but also good displacement-limiting ability and self-recentering ability,and traditional horizontal isolation bearing is difficult to meet the above requirements.At the same time,some main transformer equipments also include inclined ceramic sleeves that are sensitive to vertical ground motions,which also puts forward higher requirements for vertical isolation.In this paper,the metallic rubber material with excellent properties such as strain hardening,stable mechanical properties and strong environmental adaptability is used to fill the metallic rubber isolation ring into the friction pendulum bearing to form the friction pendulum metallic rubber joint horizontal isolation bearing;A vertical isolation system with good isolation performance is constructed by using linear spring and nonlinear viscous damper in parallel;Based on this,theoretical,simulation and shaking table tests are carried out to analyze and verify the effectiveness of the three-dimensional isolation system of main transformer equipment and the correctness of the design method.The specific research contents of this paper are as follows:(1)Based on the nonlinear metallic rubber material,a three-dimensional(3-D)isolation system for main transformer equipment is proposed.In order to study the stiffness and damping characteristics of the horizontal combined isolation bearing and the vertical isolation component,the mechanical performance tests are carried out.Based on the force displacement relationship curve of 3-D isolation bearing,the mechanical models of metallic rubber isolation ring,horizontal isolation bearing and vertical isolation bearing are established.(2)According to the proposed mechanical model of three-dimensional isolation bearing,the estimation method of bearing parameters is proposed.Based on the finite element simulation analysis,the parameter optimization design process of horizontal isolation and vertical isolation is proposed,and the isolation effect under one-way and three-way loading is analyzed and verified.The isolation parameters of the corresponding scaled-model are obtained.(3)Shaking table test is used to study the performance of three-dimensional variable stiffness isolation system of main transformer equipment.The response differences of three-dimensional isolation efficiency,peak displacement and residual displacement between main transformer equipment seismic isolation system and three-dimensional isolation system under unidirectional,bidirectional and three-dimensional loading conditions are compared and analyzed.The effectiveness of three-dimensional isolation system and the feasibility of design method are analyzed and verified.(4)In order to confirm the correctness and rationality of the finite element analysis method,numerical simulation and shaking table test of 3-D isolation of main transformer equipment were carried out,and the seismic response of main transformer equipment with metallic rubber-friction pendulum combined isolation bearing and only friction pendulum bearing was further compared and analyzed,so as to verify the isolation performance of the new variable stiffness 3-D isolation system and effectiveness and applicability of selflimiting performance. |
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