Effect of near-fault earthquake on bridges: lessons learned from Chi-Chi earthquake

Loh, Chin‐Hsiung; Liao, Wei-Hsin; Chai, Juin‐Fu

doi:10.1007/s11803-002-0011-3

Cited by 28 publications

(14 citation statements)

References 4 publications

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“…NF ground motions may have more distinct characteristics than FF ground motions (e.g., directivity, spectral nonstationarity, intensity, duration, frequency content characteristics, and directionality of components) and have significant influence on the seismic response of bridges as realized in the recent bridge reconnaissance. (Chang et al 2000;Loh et al 2002), analytical (Billah et al 2012;Dimitrakopoulos 2011;Jalali et al 2012;Liao et al 2004;Ozbulut and Hurlebaus 2012;Shi and Dimitrakopoulos 2017), and experimental studies (Choi et al 2010;Phan et al 2007;Saaidi et al 2012). Liao et al (2004) compared the dynamic response of box-girder bridges in Taiwan, and noted that the ratio of peak ground velocity to acceleration is the key factor that governs the response of bridges under NF ground motions.…”

Section: Introductionmentioning

confidence: 99%

Skew Adjustment Factors for Fragilities of California Box-Girder Bridges Subjected to near-Fault and Far-Field Ground Motions

2019

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Past reconnaissance studies revealed that bridges close to active faults are more susceptible to damage and more than 60% of the bridges in California are skewed. To assess the combined effect of near-fault ground motions and skewness, this paper evaluates the seismic vulnerability of skewed concrete box-girder bridges in California subjected to near-fault and far-field ground motions. The relative risk of skewness and fault-location on the bridges is evaluated by developing fragility curves of bridge components and system accounting for the material, geometric, and structural uncertainties. It is noted that the skewness and bridge site close to active faults make bridges more vulnerable, and the existing modification factor in HAZUS cannot capture the variation in the median value of the fragilities appropriately. A new set of fragility adjustment factors for skewness coupled with the effect of fault location is suggested in this paper.

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Section: Introductionmentioning

confidence: 99%

Skew Adjustment Factors for Fragilities of California Box-Girder Bridges Subjected to near-Fault and Far-Field Ground Motions

2019

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Mosleh¹,

Razzaghi²,

Jara³

et al. 2016

Earthquakes and Structures

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This paper presents a probabilistic fragility analysis for two groups of bridges: simply supported and integral bridges. Comparisons are based on the seismic fragility of the bridges subjected to accelerograms of two seismic sources. Three-dimensional finite-element models of the bridges were created for each set of bridge samples, considering the nonlinear behaviour of critical bridge components. When the seismic hazard in the site is controlled by a few seismic sources, it is important to quantify separately the contribution of each fault to the structure vulnerability. In this study, seismic records come from earthquakes that originated in strike-slip and reverse faulting mechanisms. The influence of the earthquake mechanism on the seismic vulnerability of the bridges was analysed by considering the displacement ductility of the piers. An in-depth parametric study was conducted to evaluate the sensitivity of the bridges' seismic responses to variations of structural parameters. The analysis showed that uncertainties related to the presence of lap splices in columns and superstructure type in terms of integral or simply supported spans should be considered in the fragility analysis of the bridge system. Finally, the fragility curves determine the conditional probabilities that a specific structural demand will reach or exceed the structural capacity by considering peak ground acceleration (PGA) and acceleration spectrum intensity (ASI). The results also show that the simply supported bridges perform consistently better from a seismic perspective than integral bridges and focal mechanism of the earthquakes plays an important role in the seismic fragility analysis of highway bridges.

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“…Near-fault ground motion can introduce more devastating response to isolated structures than an equal or larger (higher peak ground acceleration) far-field ground motion (Loh et al, 2002). This concern profoundly influenced seismic isolation design requirements in the 1997 Uniform Building Code (ICBO, 1997).…”

Section: Introductionmentioning

confidence: 99%

Seismic response of liquid storage steel tanks with variable frequency pendulum isolator

Panchal¹,

Jangid

2011

KSCE J Civ Eng

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The seismic response of liquid storage steel tanks (slender and broad) isolated with Variable Frequency Pendulum Isolators (VFPIs) is investigated under normal component of six near-fault ground motions. The continuous liquid mass is lumped as convective mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses is worked out depending upon the properties of the tank wall and liquid mass. The frictional forces mobilized at the interface of the VFPI are assumed to be velocity independent. The governing equations of motion of liquid storage steel tanks isolated with the VFPIs are derived and solved in the incremental form using Newmark's step-by-step method assuming linear variation of acceleration over small time interval. For comparative study, the seismic response of liquid storage steel tanks with the VFPIs is compared with that of the same liquid storage steel tanks isolated using the Friction Pendulum Systems (FPSs). In order to measure the effectiveness of isolation system, the seismic response of isolated steel tanks is compared with that of the non-isolated steel tanks. Further, a parametric study has been carried out to critically examine the behaviour of liquid storage steel tanks isolated with VFPIs. The important parameters considered are the friction coefficient of the VFPI, the Frequency Variation Factor (FVF) of the VFPI and the tank aspect ratio. The difference between the liquid storage tanks isolated with the VFPI and the FPS isolators subjected to the harmonic and far-field ground motions was also investigated in this study. Effect of vertical component of ground motions on the behaviour of the VFPI-isolated liquid storage tanks is investigated under triaxial ground excitations by considering the interaction of forces in two orthogonal directions. From these investigations, it is concluded that seismic response, viz. the base shear, the sloshing displacement and the impulsive displacement, of liquid storage steel tanks during near-fault ground motions can be controlled within a desirable range with the installation of the VFPI. Under strong harmonic excitations, the base shear of the VFPI reduces than that of the FPS whereas the sloshing displacement, the impulsive displacement and the isolator displacement of the VFPI exceeds than that of the FPS. It is also found that the isolation by the FPS and VFPI isolators has almost the same effect in the tank to the far-field ground motions. The triaxial ground motions have noticeable effect on the response of the VFPI-isolated liquid storage tanks relative to unilateral ground motion and if ignored, the sliding displacement and base shear will be underestimated.

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Effect of near-fault earthquake on bridges: lessons learned from Chi-Chi earthquake

Cited by 28 publications

References 4 publications

Skew Adjustment Factors for Fragilities of California Box-Girder Bridges Subjected to near-Fault and Far-Field Ground Motions

Skew Adjustment Factors for Fragilities of California Box-Girder Bridges Subjected to near-Fault and Far-Field Ground Motions

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

Seismic response of liquid storage steel tanks with variable frequency pendulum isolator

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