An Impedance Model Approach to Predicting Train-Induced Vibrations in Buildings

In major cities around the world, urbanization and rising land prices have been driving an increase in real estate development adjacent to, and above in many cases, railway lines and other transportation corridors. Structure-borne sound and vibrations from traffic can be are annoying to human occupants; if high, they can also be disruptive to operation of manufacturing facilities, medical facilities, and research laboratories. As awareness of structure-borne sound and vibration issues grow among owners, designers, and building occupants, there is a corresponding increase in demand for cost effective sound and vibration predictions and mitigation. This research describes the development and verification of an analytical model of vibration transmission in an existing four-story building in Boston that is based on the floor and column impedances where they are attached. Using geometric properties, the authors defined the dynamic behavior of the test structure in terms of column impedances (modeled as finite, wave propagating rods) and floor impedances (modeled as energy dissipating, infinite plates). Researchers performed impact hammer tests as means of verifying the floor impedances, and also collected shaker and train-induced vibration measurements near the test column. The authors highlight several aspects of this modeling approach, and discuss the effectiveness of using this approach to predict the vibration response of buildings subject to ground-borne vibrations.