层状土层随机地震反应分析的近似解法

AN APPROACH TO SOLVE RANDOM SEISMIC RESPONSE OF LAYERED SOIL

基于模态摄动方法,提出了层状土层随机地震反应的近似分析方法。该方法首先利用等效均匀剪切梁的模态和频率,将层状土层的微分方程转化为代数方程,得到层状土层的固有频率和模态。在此基础上,推导了层状土层随机地震反应的计算公式。最后通过算例,阐述了基于模态摄动法进行随机地震反应的计算过程并分析了该方法的计算误差。计算结果表明,这一方法简单有效,其误差可控制在5%以内。

Based on modal perturbation method, a new response of horizontal layered soil. In the approach, the approach is developed for solving the random seismic dynamic characteristics of layered soil are calculated approximately in the modal subspace spanned by several lower models, of equivalent homogeneous shear beam with the same depth, average shear modulus and mass density. As a result, the differential vibration equation of soil layer with variable properties is transferred as a set of algebraic equations. Then the equation of random seismic response of layered soil is derived. By way of numerical example, the procedure and calculation error of random seismic response by using mode perturbation is discussed. Numerical results show that the approach is simple and practicable, that error is less than 5%.