Abstract
Highly inelastic nonlinear interaction of liquefied soil and underground RC ducts is computationally investigated in view of the structural damage. The required ductility is expected to be insensitive to the risk of liquefaction for normally deposited layers of soil, and the lesser ductility is acceptable for the case of highly liquefiable foundation similar to the seismic isolation. Although the structural nonlinearity has a fewer effect on the uplift of the underground ducts, the amount of main reinforcement may control the structural damage with the same efficiency for both drained and undrained soil deposits.