Issues and limitations on measuring building’s transfer function

In the planning stages for new buildings or transit systems, the effects of railway induced ground-borne vibration need to be considered. The propagation of vibration from the ground to a receiving room is a complex problem. It is common practise, within vibration assessment, for the buildings vibration response to be acquired empirically by ether measuring the response of the building in question via an impact method, measuring the response on an equivalent type of building, or using pre existing published data (from the 70s and 80s) to derive a ground to building transfer functions. This paper compares, as a method of evaluating a building transfer function, impact method with actual rail pass-bys and recently collected response with published generalised response curves. The results presented suggests that, when using the impact method excitation process (point source), the distance of impact location to the building foundation is critical, drastically affecting the resulting transfer function. In addition when using train pass-bys as the excitation process, train length is shown to have an influence on the transfer function assessed. The pre-published data are also shown to have limitations for more recent types of construction.