质量-弹簧模型在储液容器抗震分析中的应用

摘要

核电厂有很多储液容器,对这些储液容器进行抗震分析时,液体的晃动可明显改变容器的质心和转动惯量等一些力学参数,因此,液体晃动对设备造成的载荷是不可忽略的.质量-弹簧模型是Housner理论和ASCE-4-98规范中对储液容器在地震作用下承受的液动压力给出的简化计算模型.本工作依据Housner理论和ASCE-4-98规范,对储液容器和容器内液体建立了三维质量-弹簧有限元模型,并据此计算了核电厂的储液容器在承受水平地震载荷时液体的作用力.将计算得到的液体频率结果及对流液体对容器的作用结果与应用公式计算的结果进行比较表明,三维有限元模型的计算结果是合理、可靠的.与ASCE-4-98规范相比,将质量-弹簧模型应用到三维有限元模型中,可直接从地震输入的模型中得到板壳元或三维实体有限元上位移和应力分布结果,这样更为直观方便.%There are many tanks for storing liquid in nuclear power plant.When seismic analysis is performed,swaying of liquid may change the mechanical parameters of those tanks,such as the center of mass and the moment of inertia,etc.,so the load due to swaying of liquid can't be neglected.Mass-spring model is a simplified model to calculate the dynamic pressure of liquid in tank under earthquake,which is derived by the theory of Housner and given in the specification of seismic analysis of Safety-Related Nuclear Structures and Commentary-4-98 (ASCE-4-98 for short hereinafter).According to the theory of Housner and ASCE-4-98,the mass-spring 3-D FEM model for storage tank and liquid in it was established,by which the force of stored liquid acted on liquid storage tank in nuclear power plant under horizontal seismic load was calculated.The calculated frequency of liquid swaying and effect of liquid convection on storagetank were compared with those calculated by simplified formula.It is shown that the results of 3-D FEM model are reasonable and reliable.Further more,it is more direct and convenient compared with description in ASCE-4-98 when the mass-spring model is applied to 3-D FEM model for seismic analysis,from which the displacement and stress distributions of the plate-shell elements or the 3-D solid finite elements can be obtained directly from the seismic input model.