Seismic fragility assessment of geotechnical seismic isolation (GSI) for bridge configuration

Davide Forcellini,Saif Alzabeebee

doi:10.1007/s10518-022-01356-5

Abstract

The seismic vulnerability of bridges may be reduced by the application of Geotechnical Seismic Isolation (GSI) below the foundations of the columns and the abutments. However, the role of GSI on the seismic response of bridges has been limitedly examined in literature. Therefore, this research has been conducted to study the effect of applying GSI on the seismic response of bridges to address the aforementioned gap in knowledge. Advanced nonlinear dynamic three-dimensional finite element analyses have been conducted using OpenSees to study the influence of the GSI. The cases of traditional and isolated bridges subjected to earthquakes have been considered to assess the GSI effects. The results showed that the GSI reduces the seismic effect on the column while its effect seems to be less significant for the abutments. In addition, fragility curves for the traditional and isolated cases have been developed and compared to provide insights with a probabilistic-based approach. The results of this paper provide a useful benchmark for design considerations regarding the use of GSI for bridges.

Highlights

Geotechnical Seismic Isolation (GSI) may be considered as an innovative method to reduce the seismic vulnerability of civil structures and infrastructures
This paper investigated the influence of the GSI on the seismic vulnerability of a benchmark bridge configuration representing a typical Californian highway two-span concrete bridge
Three-dimensional soil-foundation-structure numerical models were performed with OpenSees to derive analytical fragility curves that describe the vulnerability of the columns and the abutments

Summary

Introduction

Geotechnical Seismic Isolation (GSI) may be considered as an innovative method to reduce the seismic vulnerability of civil structures and infrastructures. The use of the GSI has been examined by several researchers (e.g., Tsang 2009; Tsang et al 2012). Tsang (2009) introduced the definition of the GSI itself. Tsang et al (2012) examined the use of rubber–soil mixtures on the acceleration and inter-story drift of low to medium rise. Equivalent liner model was used to model the dynamic response of the soil and the GSI in Tsang et al (2012) study, where the dynamic response of the soil was characterized using the secant shear modulus and the damping ratio. Forcellini (2017) investigated the effect of the thickness of the GSI on the response of a bridge using different earthquake records with a PGA range of 0.3–0.9 g. Forcellini (2017) used granulated rubber–soil mixtures as the GSI material Equivalent liner model was used to model the dynamic response of the soil and the GSI in Tsang et al (2012) study, where the dynamic response of the soil was characterized using the secant shear modulus and the damping ratio. Forcellini (2017) investigated the effect of the thickness of the GSI on the response of a bridge using different earthquake records with a PGA range of 0.3–0.9 g. Forcellini (2017) used granulated rubber–soil mixtures as the GSI material

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