پیمان نرج آبادی فام

Geosynthetic aseismic isolation (GAI) provides economic alternatives to currently used isolation systems. Self-centering capability (SC) is a technical requirement in aseismic isolation and mandated by seismic design codes. SC of GAI systems is investigated and evaluated in this paper. The method of research is parametric study, referring to practical design parameters and code-based criteria. Experimentally validated interfaces made up of high-density polyethylene (HDPE)-type geomembrane layer placing under high-strength nonwoven geotextile layer, ultrahigh molecular weight polyethylene (UHMWPE)-type geomembrane placing under high-strength nonwoven geotextile, and geomembrane layer in lubricated contact with another layer of geomembrane are the interfaces studied as GAI liners, all with spherical configuration which is well accepted as a practical configuration. A phenomenological model verified by published experiments is used in the computer simulations, and a database of near and far-fault ground motion records is used in the analyses. Displacement responses obtained from time-history analyses are examined with reference to the specifications of the codes, and relating engineering considerations are discussed. It is shown that GAI systems ensure sufficient SC, with residual displacements less than those allowed by the codes. Regarding the geometrical requirements for acceptable SC, lubricated GAIs are suggested for earthquake protection of large-scale structures like multi-story buildings. Non-lubricated GAIs, such as the geotextile/UHMWPE, are suggested in the cases of some types of structures like water tanks