ANSYS黏弹性边界在拱坝抗震分析中的应用

摘要

Dam⁃reservoir interaction, radiation damping effect and the correct seismic motion input method are important factors affecting seismic response of dam structure. In this paper, the hydrodynamic pressure applying subroutine and external source wave input subroutine of three⁃dimensional viscoelastic artificial boundary were achieved by APDL language based on the Westergaard add mass method, wave motion theories and the commercial nonlinear finite element code ANSYS. Finally, the additional mass element, the viscous-spring boundary element and wave input method were applied to the dynamic analysis of a concrete arch dam, and MISO and linear elastic models provided by ANSYS were used in the analysis of the seismic response of dam. The results show that the artificial boundary gives more accurate simulation of seismic wave transmission by considering external waves far field energy dissipation, and the element stress reduces and node displacement increases with the consideration of the material nonlinearity of the dam concrete, which is more aligned with the realistic seismic response of the concrete dam.%坝体－库水相互作用、地基辐射阻尼效应和地震波动输入方式是影响坝体地震响应的重要因素。基于大型非线性有限元程序ANSYS，利用APDL语言编写了施加动水压力、三维黏弹性边界和外源波动输入子程序。最后将该程序应用到某拱坝的地震响应分析中，并将ANSYS中的多线性等向强化模型与线弹性模型计算的结果进行了对比。结果表明：黏弹性人工边界考虑了地震波的远域能量逸散，其计算结果更加合理；考虑了材料非线性后，坝体单元应力有所减小，节点位移有所增大，更符合坝体实际的地震响应。