Structural Response Spectra under Passing Underground Trains

The vibrations due to passing of underground trains can harm nonstructural elements and disturb the occupants of nearby buildings. Importance of the problems raised are more highlighted for buildings like hospitals, laboratories, museums, etc., and their assessments is an important design need. As a response to this necessity, in this paper response spectra for buildings due to passing trains moving with different velocities are calculated. These spectra are very convenient substitutes for the time consuming and costly analysis of a tunnel-soil system under moving loads, as they give the maximum structural responses rapidly. For derivation of the spectra, the soil-tunnel system is modeled using a 3D finite element mesh and the standard moving train loads are applied to the system. The ground surface vibration time histories are calculated at different distances from the tunnel axis. The peak acceleration, velocity, and displacement responses are determined for an SDF dynamical system under the same ground motions. Different standard trains, train velocities, tunnel depths, distances from tunnel, and soil types are taken into account and the results of the analysis are presented as acceleration, velocity, and displacement spectra.