Study on seismic performance and index limits quantification for prefabricated subway station structures

Three-dimensional nonlinear finite element analyses are conducted to evaluate the seismic performance of rectangular prefabricated and cast-in-place underground structures considering soil-structure interaction. The finite element models are developed based on a prefabricated subway station project in Beijing. The seismic loading conditions, damage evolution, structure deformation, internal forces and the performance index limits values are compared for prefabricated (assembly monolithic (AMT) and assembly spliced (ASF)) and cast-in -place (CIP) underground structures. Numerical results indicated that the degree of plastic damage at center column of prefabricated underground structure was less than that for CIP underground structure. The failure mechanism of both types of underground structures was the same, the central column first lost its bearing ca-pacity then the side wall failed. The column's internal force of ASF structure was significantly reduced compared with that of CIP structure, and the most unfavorable seismic position of the three structures is the bottom of the lower column. It was also found that vertical ground motion can significantly accelerate prefabricated under-ground structural destroy, but it has little effect on the horizontal displacement. Finally, index limits are quantified for four seismic performance levels of prefabricated underground structures, which can be considered in performance-based design of prefabricated underground structures.