Shaking Table Tests on Seismic Responses of Atrium-style Subway Station

The ceiling and middle slabs of an atrium-style subway station are both replaced with flat-beams to form a large atrium (the opening area is about 50% of the floorage of each story). There is no column at the station hall floor and thin-walled columns with a width-to-height ratio of 7.5 are adopted at the platform floor. With such a building style, the capabilities of the station to withstand lateral action such as seismic action become a major concern. In this study, a series of 1 g shaking table tests were carried out on an atrium-style subway station embedded in artificial soil under different earthquake intensities. Experiments were conducted to investigate the seismic characteristics of the soil and subway station including the influence of earthquake intensity. Experimental results show that the two ends of the beams on the station hall floor, with the largest dynamic tensile strains, are the most vulnerable sections of the atrium-style subway station when an earthquake occurs. The differences in horizontal acceleration amplitude between the sidewall and adjacent soil vary at different depths. It was also discovered that the intensity of the earthquake has a significant influence on the seismic responses of both the station structure and surrounding ground. With increasing earthquake intensity, the predominant frequencies at different soil depths tend to be less significant while the high-amplitude spectra tend to lie mainly in a quite wider frequency band. The differences in acceleration amplification factor at the depth of the ceiling slab between the sidewall and the adjacent soil decrease with increasing earthquake intensity. The distribution of dynamic soil normal stresses along the sidewall may change its shape as earthquake intensity increases. The peak stresses are asymmetric for the left and right sidewalls. Under horizontal earthquake excitation, there is a rocking mode of vibration for the atrium-style station. The higher amplitude of horizontal input motion leads to larger vertical accelerations of the station ceiling slab. The conclusions of the experiment contribute to understanding the seismic characteristics of atrium-style underground structures better, and also provide references for the seismic design.