Experiments of an atrium-style metro station under harmonic excitation

The atrium-style station is one of the favourite choices in underground railway systems, as it can provide a larger and clearer space for passengers and commercial clients at the hall level of the station. With such style, as hall slabs are replaced with flat-beams, the station's capabilities to withstand lateral action like seismic action become one of the main concerns. Shaking table tests were conducted to investigate the dynamic response of soil-structure interaction of atrium-style station model under harmonic excitations covering the full frequency range, with comparison to free-field tests. The experimental results confirm that the influence of the structure on the dynamic response of the ground surface begins when the frequency of input motions is greater than 10 Hz. The predominant frequencies of the ground corresponding to the second and third modes both show an increase of 10% from the FF model to the SS model due to the presence of an atrium-style metro station. For atrium-style station: (i) the discontinuous structural elements such as beams and columns are more severely strained than the continuous ones like slabs and side walls, (ii) the peak dynamic soil normal stresses along the side wall follow an approximate L-shaped distribution and the maximum stress occurs at the side wall bottom, and (iii) the spectral characteristics of both dynamic structural strain and dynamic soil normal stress reflect the amplification function of the ground.