Seismic soil-structure interaction: Beneficial or detrimental?

George Mylonakis, George Gazetas

Research output: Contribution to journalArticle (Academic Journal)peer-review

540 Citations (Scopus)


The role of soil-structure interaction (SSI) in the seismic response of structures is reexplored using recorded motions and theoretical considerations. Firstly, the way current seismic provisions treat SSI effects is briefly discussed. The idealised design spectra of the codes along with the increased fundamental period and effective damping due to SSI lead invariably to reduced forces in the structure. Reality, however, often differs from this view. It is shown that, in certain seismic and soil environments, an increase in the fundamental natural period of a moderately flexible structure due to SSI may have a detrimental effect on the imposed seismic demand. Secondly, a widely used structural model for assessing SSI effects on inelastic bridge piers is examined. Using theoretical arguments and rigorous numerical analyses it is shown that indiscriminate use of ductility concepts and geometric relations may lead to erroneous conclusions in the assessment of seismic performance. Numerical examples are presented which highlight critical issues of the problem.

Original languageEnglish
Pages (from-to)277-301
Number of pages25
JournalJournal of Earthquake Engineering
Issue number3
Publication statusPublished - 1 Jan 2000


  • Bridge
  • Ductility
  • Earthquake
  • Inelastic response
  • Seismic regulations
  • Soil-structure interaction


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