非匀质场地地震反应的模态叠加法解

将模态叠加法应用于刚性基岩上、受竖直向上传播的稳态剪切地震波激振下剪切刚度沿深度按指数规律增长的单层非匀质场地土模型的地震反应分析,求得有效振型参与系数的解.在算例分析中将此类非匀质场地与剪切波速取为平均值的匀质场地的有效振型参与系数进行了比较,并验证了第一阶固有频率的工程估算式仍可用于此类非匀质场地,且其对估算高阶固有频率是个很重要的参数.

Seismic Response of Inhomogeneous Site by Using the Mode-superposition Method

The mode-superposition method is applied to the analysis of seismic response of an inhomogeneous site which is excited by vertically propagating shear waves. The solutions for effective modal participation factor are presented for a single layer with a shear stiffness distribution exponentially increasing with depth. In an example the solutions are compared with those of a homogeneous site with an average shear wave velocity. The example also verifies that the natural frequency for the first mode can still be estimated from the formula in engineering and is an important parameter for estimating the high mode frequencies.