Angeliki GERONTATI
Angeliki Gerontati was born in Athens, Greece in 1996. She holds a Degree (5-year program, integrated master) in Civil Engineering with major in Structural Engineering from the National Technical University of Athens (2019). Her thesis entitled “Strengthening of steel and angle members with reinforced polymers FRP” was prepared under the supervision of Mr. I. Vayas, Professor of the NTUA. She also has a MSc in Analysis and Design of Earthquake Resistant Structures from the same university (2020). She is a PhD candidate since 2020 on the assessment of power plants under seismic risk and supervising Mr. D. Vamvatsikos, Associate Professor of NTUA.
CONFERENCE PAPERS
Now - 2022
Gerontati A., Vamvatsikos D. (2023). The effect of intensity measure selection and epistemic uncertainties on the estimated seismic performance for non-structural components of nuclear powerplants. Proceedings of the SECED 2023 Conference, Cambridge, UK.
Abstract | The seismic performance of a structure/component is influenced by aleatory randomness and epistemic uncertainty, but also by the intensity measure (IM) selected for the assessment. Aleatory randomness results from natural ground motion record variability, while epistemic uncertainty corresponds to modelling assumptions, parameter variability, omissions or simplifications. IM selection, though, depends on the analyst and the data available. Potential
candidate IMs are the peak ground acceleration (a nuclear industry standard), spectral acceleration at a fundamental period of the structure (the relative newcomer), and average spectral acceleration in the range of short periods (the novel option). Their performance in quantifying uncertainty for short-period nuclear powerplants is not given, nor is it necessarily obvious given the sizeable uncertainties involved. To provide a basis for discussion, a singledegree-of-freedom non-structural component in an AP1000 reactor building is used as casestudy. Three alternative uncertainty propagation approaches are employed: (a) Monte Carlo simulation with classic Latin hypercube sampling, (b) Monte Carlo simulation with progressive Latin hypercube sampling and (c) a first-order second-moment method, representing different compromises between speed and accuracy. The resulting fragility curves of the non-structural component are compared in terms of efficiency for assessing its performance, offering evidence in support of optimizing IM selection.
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Chatzidaki A., Giannelos C., Gerontati A., Vamvatsikos D., Loli M., Tsatsis A. (2022). Seismic risk and resilience assessment for the Metsovo-Panagia segment of Egnatia Odos. Proceedings of the 5th Panhellenic Conference on Earthquake Engineering and Engineering Seismology, Athens, Greece (in greek).
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Chatzidaki A., Gerontati A., Vamvatsikos D. (2022). Seismic damage and implied traffic delay assessment for a highway bridge of Egnatia Odos Greece. Proceedings of the 3rd European Conference on Earthquake Engineering and Seismology (3ECEES), Bucharest, Romania.
Abstract | The seismic damage and the implied traffic delays are assessed for two structurally independent twin bridges, one per travel direction, which form the G7 bridge of the Egnatia highway in Greece. They are reinforced concrete structures with a monolithic pier-to-deck connection that were built using the cantilever method of construction. To enhance the seismic assessment resolution, a component-based approach is followed that allows evaluating damage scenarios for individual critical bridge components and propagating them to assess the performance of the entire system. This necessitates linking the component damages to the actions that the road operator would take in order effect repairs, i.e., by reducing the speed limit in any of the lanes and/or closing any of them until repairs are finished. These interventions typically lead to traffic delays for the entire highway that are computed on an event basis via event-based probabilistic seismic hazard analysis by considering the component-to-asset and asset-to-system interdependencies. The aim is to develop a decision support tool for pre-event risk assessment and rapid post-event inspection of critical road infrastructure by combining hazard, vulnerability and sensor
information to predict the resulting consequences both on the asset and the system level at every step during an asset’s recovery back to full functionality.
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Gerontati A., Vamvatsikos D. (2022). A comparison of three scalar intensity measures for non-structural component assessment of nuclear powerplants. Proceedings of the 3rd European Conference on Earthquake Engineering and Seismology (3ECEES), Bucharest, Romania.
Abstract | Three candidate intensity measures are compared in terms of efficiency and sufficiency for assessing the non-structural performance of nuclear powerplant components. These are the peak ground acceleration, the spectral acceleration at the fundamental period of the structure, and the average spectral acceleration in the range of short periods. To do so, single-degree-of-freedom non-structural components of different periods and capacities are considered at different locations within an AP 1000 reactor model. Incremental dynamic analysis is performed for a set of 30 records. The spectral floor accelerations of each SDOF component are monitored and capacity exceedances are recorded to assess the lognormal parameters of component fragility curves. The numerical results demonstrate that average spectral acceleration would be the most useful intensity measure in both efficiency and sufficiency, regardless of location, period or capacity, with the obvious exception of the ground surface. Nevertheless, the conventional choice of the peak ground acceleration remains a very close contender, as it leads to results of low dispersion and little bias for such stiff structures and short-period components.
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Gerontati A., Bilionis D.V., Vamvatsikos D., Tibolt M. (2022). Modular modeling and risk assessment of power transmission lines under extreme weather hazards. Proceedings of the 3rd International Conference on Natural Hazards & Infrastructure ICONHIC 2022, Athens, Greece.
Abstract | Power transmission lines are the “highways” of electricity, consisting of conductors supported on steel towers. Transmission towers are categorized as support or angle/dead-end based on their capability to resist along-line loads transmitted by the conductors. They are vulnerable to severe weather and in particular the combination of high winds and ice accretion that could lead to catastrophic failures. It is thus of great interest in the system design to arrest the propagation of a single tower failure that may trigger a series of failures of adjacent ones, considerably lengthening the duration of power outage. A modular multi-span model of a power line is proposed for the assessment of the behavior of the tower-line system and the severity evaluation of such failures. Fault tree analysis is employed to examine the failure propagation to adjacent towers under extreme weather hazard, which allows the assessment of consequences at the level of an entire system of interleaved support and angle/dead-end transmission towers. The aggregated economic losses for an operational lifetime of 60 years are investigated using the proposed model versus a simplified approach, where all towers are exclusively characterized as support ones without considering successive failures.
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