SEISMIC RELIABILITY OF BUILDINGS WITH GEOTECHNICAL SEISMIC ISOLATION (GSI)

Abstract

The article is devoted to the study of the seismic reliability of a building with geotechnical seismic isolation (GSI) under earthquakes of a given intensity. The aim of the work is the numerical modeling of the seismic reliability of buildings with geotechnical seismic isolation, including the analysis of geotechnical parameters, dynamic modeling, probabilistic assessment of the risk of foundation deformations, and the dynamic behavior of the building under earthquakes of a given intensity. The results of the study of geotechnical seismic isolation (GSI) parameters made of various geomaterials such as sand, gravel, and crushed stone are presented, along with the results of numerical modeling of the dynamic behavior of the building, the results of reliability assessment in terms of settlement, and the probabilities of exceeding the allowable acceleration at the foundation and at the top of the building, as well as the patterns of reducing the seismic response depending on the characteristics of geotechnical seismic isolation (GSI). The interaction of geotechnical seismic isolation and the superstructure was modeled in the Plaxis 2D program using the finite element method with an earthquake accelerogram corresponding to the Kobe earthquake (1995, Mw 6.9) with a duration of 20 s. The analysis of the amplitude–frequency characteristics of the building vibrations shows that as the height and volume of geotechnical seismic isolation (GSI) increase, horizontal accelerations at the top and at the foundation level decrease by 16%. A significant reduction of acceleration by 15% and of foundation settlement by 9% is observed when geotechnical seismic isolation (GSI) is constructed from coarse sand. Reinforcement of geotechnical seismic isolation (GSI) made of coarse sand with a geogrid shows a reduction in the amplitude–frequency characteristics of building vibrations by up to 28%. The analysis of the reliability coefficients of geotechnical seismic isolation (GSI) in terms of settlement and the probabilities of exceeding acceleration also shows a significant reduction in the limit of allowable acceleration at the top of the structure from 27% to 7.84%, and the reliability coefficient for acceleration β_at = 1.42, which increases by 73%. The results confirm the positive effect of using a geotechnical seismic isolation system as an economically advantageous design alternative to the traditional seismic isolation system.