A combined approach for base isolation design

Abstract

New buildings in the vicinity of underground railway lines should be protected against noise and vibrations induced by railway traffic. In the present paper a case study is presented. A 2D FEM model of the tunnel, ground and building was built in order to identify the transfer function of vibration from the tunnel to building foundations. A 3D model of the building was built, including not only structural elements, but also other non structural walls, in order to identify the transfer function of vibration from foundations to walls and floors. As the impedance of heavy walls and floors is much higher than the acoustic impedance of air, the numerically assessed vibration fields of walls and floors were used to calculate sound fields in rooms by means of natural mode analysis. The vibration and sound fields were then compared with comfort criteria in order to design a base isolation system. With this combined approach, the analysis was performed up to 170 Hz, which is more than one can usually do with integrated 3D models.