Seismic performance levels of frame-type subway underground station with three layers and three spans

According to the rules in the seismic code of China, six different site classifications are designed and expanded. Considering the effects of diaphragm walls and input ground motion intensity, the dynamic damage characteristics, failure process and seismic performance of subway underground stations with three layers and three spans are studied. The numerical results show that when the magnitude of the interlayer displacement angle is close, the damage degree of the structure is the smallest under the condition of the second-class site and the most serious under that of the fourth-class site. In case of large earthquake and poor site conditions, the structure is in a state of serious damage for a period of time after the peak value of input ground motion, and then it enters into a state of possible total destruction. Based on the calculated results, the prediction formulas for the interlayer displacement angles and the structure-site stiffness ratio of the subway underground station structure are established. Finally, according to the relationship between the seismic damage state and the interlayer displacement angles, the seismic performance of subway underground stations is divided into five levels and described.