Isolation Performance And Numerical Algorithm Of Buildings Using Periodic Foundations

Periodic structures exhibit a unique dynamic characteristic called the frequency band gap, which lends a new insight into the isolation of vibration in engineering. Based on the frequency band gap enjoyed by periodic structures, three different periodic foundations are then designed. The concept is to employ periodic foundation to block seismic wave whose frequency falls into the frequency gap. So this thesis carries out theoretical analysis and numerical analysis on periodic structures. The contents include:1. In order to obtain low frequency gap, by introducing Bloch-Floquet theorem and elastic dynamic theory, derives the differential quadrature method formulae and Matlab codes for calculation of flexural vibration band gap. Compared with Wavelet method, the present DQM has better convergence and accuracy.2. A finite element model of two-dimensional (2D) periodic structure is built by COMSOL Multiphysics through applying periodic boundary conditions, and then the band gaps in 2D periodic foundations are obtained conveniently.3. Using ANSYS, the thesis presents harmonic responses and transient responses comparison between periodic, concrete and traditional isolation foundation forced ground acceleration. It is found that when the frequency falls into the gap, there is strong attenuation in periodic foundation and its application in seismic isolation is pretty promising.