Modelling of structures of infinite extent for calculation of vibration transmission

A methodology is presented for the calculation of ground-vibration transmission into large structures, and in particular into multi-storey buildings above underground railway lines. The dynamic-stiffness-matrix method is used to obtain a computationally-efficient method for predicting the vibration response of large structures and the method is extended with advantage to consider structures of infinite length. The interaction of such structures with piled foundations is also included. Dynamic modelling is two-dimensional, obtained by assembling columns and beams (used to represent the walls and floors) into repeating units. The units are assembled so as to obtain the exact dynamic response of large structures over a wide frequency range. The numerical value of damping is found not to be a critical factor on account of radiation to infinity through the structure and into the piled foundation. This work has application to the design of base isolation for buildings near railways and comparisons are made with measured data in a building above a railway in London.