Seismic fragility curves of shallow tunnels in alluvial deposits

Argyroudis, Sotirios; Pitilakis, Kyriazis

doi:10.1016/j.soildyn.2011.11.004

Cited by 213 publications

(95 citation statements)

References 21 publications

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“…There are parametric (e.g., log-normal function) and non-parametric method (e.g., binned Monte Carlo simulation and Kernel density estimation [28]) to establish fragility curve. In this study, the log-normal cumulative distribution function is used to define the fragility function [29][30][31][32][33].…”

Section: Fragility Curve Developmentmentioning

confidence: 99%

Seismic Vulnerability Assessment of a Shallow Two-Story Underground RC Box Structure

et al. 2017

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Tunnels, culverts, and subway stations are the main parts of an integrated infrastructure system. Most of them are constructed by the cut-and-cover method at shallow depths (mainly lower than 30 m) of soil deposits, where large-scale seismic ground deformation can occur with lower stiffness and strength of the soil. Therefore, the transverse racking deformation (one of the major seismic ground deformation) due to soil shear deformations should be included in the seismic design of underground structures using cost-and time-efficient methods that can achieve robustness of design and are easily understood by engineers. This paper aims to develop a simplified but comprehensive approach relating to vulnerability assessment in the form of fragility curves on a shallow two-story reinforced concrete underground box structure constructed in a highly-weathered soil. In addition, a comparison of the results of earthquakes per peak ground acceleration (PGA) is conducted to determine the effective and appropriate number for cost-and time-benefit analysis. The ground response acceleration method for buried structures (GRAMBS) is used to analyze the behavior of the structure subjected to transverse seismic loading under quasi-static conditions. Furthermore, the damage states that indicate the exceedance level of the structural strength capacity are described by the results of nonlinear static analyses (or so-called pushover analyses). The Latin hypercube sampling technique is employed to consider the uncertainties associated with the material properties and concrete cover owing to the variation in construction conditions. Finally, a large number of artificial ground shakings satisfying the design spectrum are generated in order to develop the seismic fragility curves based on the defined damage states. It is worth noting that the number of ground motions per PGA, which is equal to or larger than 20, is a reasonable value to perform a structural analysis that produces satisfactory fragility curves.

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Section: Fragility Curve Developmentmentioning

confidence: 99%

Seismic Vulnerability Assessment of a Shallow Two-Story Underground RC Box Structure

et al. 2017

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“…The most important and useful analytical methods for calculating these deformations are Wang and Penzien methods [2, 19] and Bobet method [20]. During 1993–2003 these methods were developed based on closed-form solutions in terms of thrust, bending moment, and displacement under external loading conditions [21–27]. …”

Section: Methodsmentioning

confidence: 99%

Effect of Vertically Propagating Shear Waves on Seismic Behavior of Circular Tunnels

Akhlaghi

Nikkar

2014

The Scientific World Journal

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Seismic design loads for tunnels are characterized in terms of the deformations imposed on the structure by surrounding ground. The free-field ground deformations due to a seismic event are estimated, and the tunnel is designed to accommodate these deformations. Vertically propagating shear waves are the predominant form of earthquake loading that causes the ovaling deformations of circular tunnels to develop, resulting in a distortion of the cross sectional shape of the tunnel lining. In this paper, seismic behavior of circular tunnels has been investigated due to propagation of shear waves in the vertical direction using quasi-static analytical approaches as well as numerical methods. Analytical approaches are based on the closed-form solutions which compute the forces in the lining due to equivalent static ovaling deformations, while the numerical method carries out dynamic, nonlinear soil-structure interaction analysis. Based on comparisons made, the accuracy and reliability of the analytical solutions are evaluated and discussed. The results show that the axial forces determined using the analytical approaches are in acceptable agreement with numerical analysis results, while the computed bending moments are less comparable and show significant discrepancies. The differences between the analytical approaches are also investigated and addressed.

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“…The FE domain was discretized using 2126 (for the 4.0 m embankment) and 2143 (for the 6.0 m cut) 15-noded plain strain triangular elements. [23,24]). In this part, the characteristic dimension of the elements (h) satisfies the condition h ≤ h max = V s /(6 ÷ 7)f max , where V s is the shear wave velocity and f max is the maximum frequency of the seismic motion.…”

Section: Fe Numerical Analysismentioning

confidence: 99%

Analytical seismic fragility functions for highway and railway embankments and cuts

Argyroudis

Kaynia

2015

Earthq Engng Struct Dyn

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Summary A fundamental tool in seismic risk assessment of transportation systems is the fragility curve, which describes the probability that a structure will reach or exceed a certain damage state for a given ground motion intensity. Fragility curves are usually represented by two‐parameter (median and log‐standard deviation) cumulative lognormal distributions. In this paper, a numerical approach, in the spirit of the IDA, is applied for the development of fragility curves for highways and railways on embankments and in cuts due to seismic shaking. The response of the geo‐construction to increasing levels of seismic intensity is evaluated using a 2D nonlinear finite element model, with an elasto‐plastic criterion to simulate the soil behavior. A calibration procedure is followed in order to account for the dependency of both the stiffness and the damping to the soil strain level. The effect of soil conditions and ground motion characteristics on the response of the embankment and cut is taken into account considering different typical soil profiles and seismic input motions. This study will provide input for the assessment of the vulnerability of the road/railway network regarding the performance of the embankments and cuts; therefore, the level of damage is described in terms of the permanent ground displacement in these structures. The fragility curves are estimated based on the evolution of damage with increasing earthquake intensity, which is described by PGA. The proposed approach allows the evaluation of new fragility curves considering the distinctive features of the element's geometry, the input motion, and the soil properties as well as the associated uncertainties. A relationship between the computed permanent ground displacement on the surface of the embankment and the PGA in the free field is also suggested based on the results of the numerical analyses. Finally, the proposed fragility curves are compared with existing empirical data and the limitations of their applicability are outlined. Copyright © 2015 John Wiley & Sons, Ltd.

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Seismic fragility curves of shallow tunnels in alluvial deposits

Cited by 213 publications

References 21 publications

Seismic Vulnerability Assessment of a Shallow Two-Story Underground RC Box Structure

Seismic Vulnerability Assessment of a Shallow Two-Story Underground RC Box Structure

Effect of Vertically Propagating Shear Waves on Seismic Behavior of Circular Tunnels

Analytical seismic fragility functions for highway and railway embankments and cuts

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