Evaluation of Soil-Structure Interaction and Structural Collapse in Daikai Subway Station During Kobe Earthquake

An evaluation of the collapse of a large portion of the Daikai subway station during the 1995 Kobe earthquake is presented based on results from nonlinear finite element analyses. The numerical studies focused on two main aspects: 1) evaluation of soil-structure interaction and drift demands imposed on the Daikai Subway Station, and 2) evaluation of the drift capacity of the reinforced concrete (RC) columns that collapsed during the Kobe earthquake. Results from this study indicate that the estimated drift and shear stress demands in the critical columns of the Daikai station— approximately 1.1% and 2.2 MPa, respectively—were sufficient to cause failure of the central RC columns of the Daikai station due to poor transverse reinforcement detailing combined with moderate axial load demands. On the other hand, the central RC columns of an adjacent running tunnel structure survived the earthquake motions with limited damage due to lower drift and shear stress demands (0.8% and 1.0 MPa, respectively), and the use of an enhanced transverse reinforcement detailing. The use of the Elwood-Moehle column collapse model led to the prediction of a reasonable range of drifts at which collapse was expected in the RC columns of the Daikai station.