Simplified building models with application to ground-borne vibration prediction

Ground-borne vibration is a problem of growing significance in densely populated urban areas, where demand for building space leads to development near surface and underground railways, and vibration assessment and mitigation is increasingly required. Base isolation is a vibration mitigation option which works by decoupling the vibration of a building from its foundation by inserting flexible bearings at support points. Simplified “dashpot” impedance models have recently been proposed with a view to predicting the performance of base isolation systems. These approximate the input impedance of a multi-storey building with an idealised structure, including a semi-infinite column, whilst including important details of soil-structure interaction. Such models have been compared previously with a reference portal-frame structure for predicting vibration power flow, isolation performance and the significance of the added-building effect in soil-structure interaction. The present research extends these “dashpot” models to include a plate-based representation of one or multiple floors. The suitability of these models for assessing base isolation performance, and for estimating the change in vibration level at the base of the building due to the added-building effect, is examined.