scholarly journals Risk Assessment of Aged Concrete Gravity Dam Subjected to Material Deterioration Under Seismic Excitation

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Tahmina Tasnim Nahar ◽  
Anh-Tuan Cao ◽  
Dookie Kim
Keyword(s):  
Mathematical Model ◽  
Risk Assessment ◽  
Seismic Risk ◽  
Fragility Curves ◽  
Seismic Excitation ◽  
Gravity Dam ◽  
Specific Time ◽  
Concrete Gravity Dam ◽  
Fragility Function ◽  
Cumulative Absolute Velocity

Abstract This paper proposes an approach to assess and predict the seismic risk of existing concrete gravity dams (CGDs) considering the ageing effect. The combination of fragility function and cumulative absolute velocity (CAV) depending on two failure states has been used in the analysis. It represents the time-variant degradation of the concrete structure and the conditional change of structural vulnerability in the case of the seismic excitation. Therefore, the seismic risk assessment captures here the nonlinear dynamic behavior of a concrete gravity dam through the fragility analysis. Incremental dynamic analysis for the fragility curves is adopted to state the performance of the dam in terms of different intensity measures. To assess the capacity of the aged concrete gravity dam, this research introduces a way to estimate the CAVlimit of CGDs with varying time. For a case study, an existing concrete gravity dam in Korea has been taken into consideration to apply this approach. The numerical finite element model is validated by optimizing the recorded field data. The proposed approach and its findings will be helpful to CGDs operators to ensure whether a dam needs to stop after a specific time using the extracted mathematical model. Furthermore, as this mathematical model is the function of time, the operator can get an idea about dam conditions at any specific time and can take necessary steps.

Seismic risk assessment of RC curved bridges through fragility curves

2019 ◽  
Author(s):  
Nina N. Serdar ◽  
Jelena R. Pejovic ◽  
Radenko Pejovic ◽  
Miloš Knežević
Keyword(s):  
Risk Assessment ◽  
Urban Areas ◽  
Seismic Risk ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Curved Bridges ◽  
Damage State ◽  
Seismic Risk Assessment ◽  
Probability Of Exceedance ◽  
Damage States

<p>It is of great importance that traffic network is still functioning in post- earthquake period, so that interventions in emergency situations are not delayed. Bridges are part of the traffic system that can be considered as critical for adequate post-earthquake response. Their seismic response often dominate the response and reliability of overall transportation system, so special attention should be given to risk assessment for these structures. In seismic vulnerability and risk assessment bridges are often classified as regular or irregular structures, dependant on their configuration. Curved bridges are considered as irregular and unexpected behaviour during seismic excitation is noticed in past earthquake events. Still there are an increasing number of these structures especially in densely populated urban areas since curved configuration is often suitable to accommodate complicated location conditions. In this paper special attention is given to seismic risk assessment of curved reinforce concrete bridges through fragility curves. Procedure for developing fragility curves is described as well as influence of radius curvature on their seismic vulnerability is investigated. Since vulnerability curves provide probability of exceedance of certain damage state, four damage states are considered: near collapse, significant damage, intermediate damage state, onset of damage and damage limitation. As much as possible these damage states are related to current European provisions. Radius of horizontal curvature is varied by changing subtended angle: 25 °, 45 ° and 90 °. Also one corresponding straight bridge is analysed. Nonlinear static procedure is used for developing of fragility curves. It was shown that probability of exceedance of certain damage states is increased as subtended angle is increased. Also it is determined that fragility of curved bridges can be related to fragility of straight counterparts what facilitates seismic evaluation of seismic vulnerability of curved bridges structures.</p>

On the Use of Proper Fragility Models for Quantitative Seismic Risk Assessment of Process Plants in Seismic Prone Areas

2017 ◽  
Author(s):  
Silvia Alessandri ◽  
Antonio C. Caputo ◽  
Daniele Corritore ◽  
Giannini Renato ◽  
Fabrizio Paolacci ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Seismic Risk ◽  
Structural Damage ◽  
Fragility Curves ◽  
Probabilistic Method ◽  
Quantitative Risk Assessment ◽  
Actual Process ◽  
Consequence Analysis ◽  
Process Plant ◽  
Process Plants

Quantitative Risk Assessment (QRA) is a classical method for the calculation of risk in process plants, which is based on the logic of the consequence analysis. This intrinsically probabilistic method has been thought for classical accident conditions, where the damage events and the relevant consequences start from a preselected component and a standard loss of containment (LOC) and follow all possible scenarios for the calculation of individual and societal risk. This final risk metric is usually expressed in terms of probability of fatality in a specific location of the surrounding area or a certain number of fatalities in the area surrounding the accident. In presence of Na-Tech events, like earthquakes, a multi-source condition can be caused by multi-damage conditions simultaneously involving more than one equipment, which in turn can generate a multiple-chain of events and consequences. In literature, several attempts of modifying the classic QRA approach to account for this important aspect have been formalized without converging toward a unified approach. In this paper, a fragility-based method for Quantitative Seismic Risk Analysis (QSRA) of a process plant is investigated. This method takes into account all possible damage/losses of containment conditions in the most critical equipment, e.g., storage tanks. Fragility curves, which are analytically evaluated for each unit with respect to its seismic damage conditions, are utilized inside the procedure. The Monte Carlo Simulation (MCS) method is then used with the aim to follow all steps of QSRA. In particular, starting from the seismic hazard curve of the site where the plant is placed, a multi-level approach is proposed. In this approach, the first level is represented by the components seismically damaged, whereas the following levels are treated through a classical consequence analysis, including the propagation of multiple simultaneous and interacting chains of accidents. These latter are applied by defining proper correspondences for all relevant equipment between structural damage (i.e., limit states) and LOC events. The application of the method to an actual process plant permits to investigate its high potentiality and the dependency of the risk assessment from the proper fragility models.

scholarly journals Damage Scenarios Simulation for Seismic Risk Assessment in Urban Zones

1996 ◽  
Vol 12 (3) ◽  
pp. 371-394 ◽  
Author(s):  
Alex H. Barbat ◽  
Fabricio Yépez Moya ◽  
JoséA. Canas
Keyword(s):  
Risk Assessment ◽  
Urban Areas ◽  
Seismic Risk ◽  
Fragility Curves ◽  
Vulnerability Index ◽  
Survey Study ◽  
Seismic Behaviour ◽  
Seismic Risk Assessment ◽  
Damage Scenarios ◽  
Damage Probability Matrices

A methodology for simulating seismic damage of unreinforced masonry buildings for seismic risk assessment of urban areas is presented in this paper. The methodology is based on the Italian vulnerability index and on the results of a post-earthquake damage survey study whose main result was an observed vulnerability function. The Monte Carlo method was then used to simulate damage probability matrices, fragility curves and vulnerability functions, all of which are the basis of a seismic risk study. The simulation process required the generation of thousands of hypothetical buildings, the analysis of their seismic behaviour and probabilistic studies of the computed results. As an example, probable damage scenarios were developed for an urban zone of Barcelona.

scholarly journals Seismic Probabilistic Risk Assessment of Nuclear Power Plants Using Response-Based Fragility Curves

2014 ◽  
Author(s):  
Ying-Hsiu Shen ◽  
Yin-Nan Huang ◽  
Ching-Ching Yu
Keyword(s):  
Risk Assessment ◽  
Boolean Algebra ◽  
Seismic Risk ◽  
Nuclear Power ◽  
Power Plants ◽  
Fragility Curves ◽  
Structural Response ◽  
Probabilistic Risk Assessment ◽  
Structural Components ◽  
Probabilistic Risk

Seismic probabilistic risk assessment (SPRA) has been widely used to compute the frequencies of core damage and release of radiation of a nuclear power plant (NPP). In 2011, Huang et al. (2011a, 2011b) published a SPRA methodology with the following characteristics different from the widely used Zion method: (a) seismic fragility curves are defined as a function of structural response parameters, such as floor spectral acceleration and story drift; (b) nonlinear response-history analysis is used to estimate statistical distributions of seismic demands for structural and non-structural components of NPPs; (c) Monte Carlo simulation is used to determine damage states of structural and non-structural components. In the study presented in this paper, the seismic risk of a sample NPP was evaluated using the methodology of Huang et al. (2011a, 2011b). The seismic risk was quantified using the annual frequency of unacceptable performance defined by a sample accident sequence for a sample NPP. The values of seismic risk computed using the methodology of Huang et al. (2011a, 2011b) and Boolean Algebra were compared to evaluate the accuracy and efficiency of the methodology of Huang et al. (2011a, 2011b). The two procedures generate similar risk values and the methodology of Huang et al. (2011a, 2011b) is more efficient than the procedure using Boolean Algebra.

Seismic Fragility Curves and Damage Probabilities of Concrete Gravity Dam Under Near–Far Faults Ground Motions

2019 ◽  
Vol 30 (1) ◽  
pp. 74-85
Author(s):  
Abdelhamid Hebbouche ◽  
Mahmoud Bensaibi ◽  
Hussein Mroueh ◽  
Mohamed Draidi Bensalah
Keyword(s):  
Fragility Curves ◽  
Ground Motions ◽  
Gravity Dam ◽  
Seismic Fragility ◽  
Concrete Gravity Dam
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