Elasto-Plastic Responses of Buried Pipeline Systems Under Wave Propagation

The purpose of this research is to study the elastic and inelastic behavior of buried pipeline system under arbitrary seismic wave propagation. Both continuous and segmented pipes with joints and junctions are included. The surrounding soil is simulated by a series of elasto-plastic springs uniformly distributed longitudinally and laterally along the pipes. To the joints, elasto-plastic longitudinal springs and bilinear rotational springs are adopted. It is assumed that the pipes remain linearly elastic. The effects of soil liquefaction and fault movement are not considered. Since the dynamic effect has been found to be negligible, a quasi-static analysis is adopted in this study. In use of the finite element technique, the equations of static equilibrium at any particular time have been obtained and a rigorous procedure for solving the inelastic responses of buried pipeline considering hysteretic responses buried characteristics of soil and joints is developed. The effects of wave forms, pipe sizes, wave velocities and incident angles are investigated with various combinations of soil and joint properties. The comparison of elastic and inelastic analysis is also done. Recommendations for future seismic design of buried pipeline systems are drawn