Earthquake damage and seismic response analysis of subway station and tunnels during the great Hanshin-Awaji earthquake

A detailed reconnaissance survey was conducted at the subway station and tunnels. Among them, Daikai subway station is the first subway structure that completely collapsed due to an earthquake. A complete collapse occurred at the location of more than half of the center columns, which resulted in the failure and collapse of the ceiling slab, and settlement of the subsoils over the station by more than 2.5 m at maximum. Many diagonal cracks were also observed on the walls in the transverse direction. Judging from the damage pattern, a strong horizontal force was imposed on the structure from the surrounding subsoils. Investigation of the damage mechanism was made through analytical approach by use of the seismic data. It is concluded that ceiling slab failed by the lack of the load carrying capacity against shear at center column.