Seismic fragility of a highway bridge in Quebec retrofitted with natural rubber isolators

Abstract

This paper presents fragility curves for the evaluation of a highway bridge retrofitted with seismic isolator devices. The object of this study is the Chemin des Dalles bridge over Highway 55 located in Trois-Rivières in Quebec, Canada. A series of synthetic ground motions time histories compatible with eastern Canada are used to capture the uncertainties related to the hazard. The seismic isolator model represents natural rubber bearing placed under the longitudinal girders over the bents and the abutments of the bridge. NRB isolators are placed in these locations to uncouple the movement of the superstructure and the infrastructure, increasing the flexibility of the system and decreasing the forces transmitted to the infrastructure. Finally, a set of fragility curves for the as-built and retrofitted models are compared to evaluate the effectiveness of seismic isolation to decrease the seismic vulnerability of this bridge.

Seismic fragility of bridges: An approach coupling multiple-stripe analysis and Gaussian mixture for multicomponent structures

“…This bridge was designed in 1975 and does not comply with current seismic design standards and detailing. It has been extensively studied and comprehensive data is available on the structural properties, capacity, site conditions, and numerical model (Roy et al, 2010;Siqueira et al, 2014b;Tavares et al, 2013;Zuluaga Rubio et al, 2019). Details on the numerical model, component capacities, and ground motion record selection are presented next.…”

“…An overview of the bridge model as well as some details on bents, columns, and abutments are illustrated in Figure 2. Further details on the numerical model and its calibration are found elsewhere (Siqueira et al, 2014b;Tavares et al 2013).…”

“…Other structural components have shown negligible seismic fragility on multi-span continuous concrete girder bridges in Eastern Canada (Siqueira et al, 2014a;Tavares et al, 2012). The associated EDPs are the deformation on the wing walls and bearings (D aww and D brg , respectively), and drift of fixed-base bent columns (d col ); all in the transverse direction (Siqueira et al, 2014b). Component capacities are assumed to follow lognormal distributions (Mangalathu and Jeon, 2019;Nielson and DesRoches, 2007) Choi et al (2004).…”