ABSTRACT
It is recognized that underground structures deforms with surrounding ground when an earthquake occurs. Therefore, seismic deformation method (SDM), where inertia of the ground is ignored and forced displacements are applied to the ground as the seismic force, is often used for seismic design. The most simplified SDM model to evaluate the longitudinal deformation of the underground structure is the elastic foundation model, where the ground is modeled as a Winkler foundation and the structure is modeled as a beam. This model is often used because of the simplicity. However, theoretical support is not sufficient. The seismic deformation method to evaluate the longitudinal bending deformation of cylindrical underground structure is reconsidered through the exact solutions based on the elastodynamics. Conventional seismic deformation method that assumes the structure as a beam overestimates the maximum axial strain of the structure because beam theory ignores the equilibrium of force in the longitudinal direction.
