Nonlinear Response of Underground Duct Structures with Due Attention to Seismic Input Ground Motions

Under destructive earthquake motions, structures behave heavily in nonlinear manner that is quite different from the linear response computation. The underground structures such as tunnels, ducts are susceptible to the ground motions so that the nonlinear interaction analysis should be performed for the reliable design. In case of irregular soil profile, due to the surface wave generation, the vertical motions come out to a less negligible extent compared to the horizontal motions. The present paper has concerned with such nonlinear response evaluation of a duct structure under strong motions. The effect of the transient characteristics in the inland type and ocean type earthquake motions is investigated. The effect of the vertical component in the ground motions is also evaluated