Effect of different steel-reinforced elastomeric isolators on the seismic fragility of a highway bridge

Abstract

Summary Seismic fragility assessment of highway bridges is a technique to predict the probability of the structure reaching a certain level of damage under a given seismic excitation. Vulnerable structural components have significant contributions to the failure probability of a bridge system. The effect of elastomeric isolators on the seismic fragility of highway bridges has been discussed in the literature; however, the impact of different types of rubber bearings, including natural rubber bearing, high‐damping rubber bearing, and lead rubber bearing has not been investigated yet. The objective of this study is to address this problem in detail. Seismic fragility of isolated bridges is analytically estimated by considering pier and isolation system as two major vulnerable components. Results showed that the isolation system is more fragile than the bridge pier. This finding represents those scenarios where the structure (and especially its seismic isolation system) is designed only according to the usually adopted probabilistic seismic hazard assessment, with a frequently insufficiently too short useful life. The bridge isolated by natural rubber bearing, which has the lowest lateral stiffness and energy dissipation capacity among considered bearings, is the most vulnerable system, and the bridge quipped with HDRB has the minimum risk to undergo damage. Copyright © 2016 John Wiley & Sons, Ltd.

Seismic performance assessment of a multispan continuous isolated highway bridge with superelastic shape memory alloy reinforced piers and restraining devices

“…The reason for using both LRB and SMA restrainers in a bridge is explained as follows. Since lead rubber bearings (LRBs) are susceptible to experience permanent displacements under destructive earthquakes, 49 SMA restrainers are used to bring the bridge back to its original position.…”

“…The initial stiffness, yield force, and postyield hardening ratio of LBRs are 14.78 kN/mm, 37.8 kN, and 0.05, respectively. The efficiency of the bilinear model in describing the actual hysteretic behavior of LRBs has been validated against the experimental results 49 . A combination of a tension‐only gap element with high stiffness and a truss element with a flag‐shaped constitutive model is used to model the SMA cable restrainers (Figure 3A).…”

“…The upper bound of the first‐order reliability theory is used to conservatively estimate the fragility of the bridge system by combining the fragilities of each bridge component 49 according to following equation. …”

Seismic assessment of earthquake‐resilient tall pier bridges using rocking foundation retrofitted with various energy dissipation devices

“…In current engineering practice for bridges, seismic isolation is usually achieved by implementing laminated rubber bearings (e.g., lead rubber bearings [LRB] and high‐damping rubber bearings [HDRB]) between superstructure and substructure 8–11 . Dezfuli and Alam 12 compared the seismic performance of various isolation bearings adopted in highway bridge, in terms of probabilistic manner using fragility analysis. The authors pointed out that when compared with the low‐damping natural rubber bearings (NRB), LRB and HDRB could effectively reduce the possibility of damage in bridge, since they possessed higher effective stiffness and energy dissipation capacity than the NRB.…”

Development of fragility curves for RC bridges subjected to reverse and strike-slip seismic sources

“…In the lack of adequate damage data or expert option, analytical fragility curves are the best choice to assess the seismic performance of highway bridges. The curves can be developed by a variety of analytical methods, such as elastic spectral method (Hwang 2000), nonlinear static analysis (Dutta and Mander 1998, Loh et al 2002, Monti and Nistico 2002, Banerjee and Shinozuka 2007, Siqueiraa et al 2014, nonlinear response history analysis (NLTHA) (Hwang et al 2001, Karim and Yamazaki 2003, Choi et al 2004, Elnashai et al 2004, Choine et al 2015, Ramanathana et al 2015, Yang et al 2015, Mosleh et al 2016a, Nateghi and Shahsavar 2004 and incremental dynamic analysis (IDA) (Billah et al 2013, Billah and Alam 2016, Dezfuli and Alam 2016. In the past decades, there have been significant researches regarding seismic vulnerability of buildings, however, less investigation has been devoted to bridges (Bojórquez et al 2012, Mollaioli et al 2013, Mosleh et al 2016b.…”