基于阻抗函数的土-基础-风机支撑结构地震响应建模方法
摘要
A Chebyshev nested lumped-parameter model (LPM) was proposed to incorporate the frequency-dependent impedances into the time history analysis of soil-foundation-wind turbine systems. The complex Chebyshev polynomials were introduced to approximate the foundation impedances with the least squares curve-fitting technique. The computational program for seismic analysis of the system was developed based on the direct integration of the governing equation in the time domain. The validity and efficiency of the computational program were verified through the comparison examples. The time history analysis of a wind turbine supported by a pile group foundation under seismic excitation shows the universality and stability of the computational program. The advantage of the Chebyshev nested LPM is that it can express the frequency-dependent impedance accurately in the time domain and avoid the high-order numerical oscillation. The nested form of the model enables wider application to different kinds of foundations. In addition, as the present model adopts no mass unit, it avoids the problem of modifying the seismic loading at the node of the foundation and makes the analysis of practical engineering more convenient.