Abstract

The Daikai station, a cut and cover structure in the subway system in Kobe, collapsed during the Hyogo ken-Nanbu earthquake of January 17, 1995 in Japan, which attracted significant attention on seismic design of underground structures world widely. Based on literature review of published researches, dynamic numerical analyses have been conducted to investigate the damage mechanism of the Daikai station subjected to the strong earthquake. The equivalent linear model has been used for the soil to approximate the nonlinear dynamic behavior of the soil including the shear modulus and the increase of damping with strain. The Concrete Damaged Plasticity model has been adopted to capture the damage evolution and progressive failure of the subway station under seismic loadings. The influence of vertical motion on the seismic response of the station is evaluated in the paper. A comparison between the numerical predictions and the damage reported shows a good agreement. The results indicate that the middle columns are the most severely damage part of the station and are mainly controlled by the horizontal ground motion. In contrast, the vertical seismic motion can generally be neglected.