Reliability Analysis of Flood and Sea Defence Structures and Systems

Risk identification consists of defining the hazard, loss causing event E, probability P(E) of that event, perception Pe(E,P(E)) and consequences C(Pe) of that perception. Risk identification is followed by risk management, whose purpose is to mitigate the risks, for example by reducing P(E) or C(Pe) and providing suitable risk communication to the population at risk. Task 7 has focused in this approach for the safety issues of flood defences on the failure probability P(E). It has been subdivided into 4 activities: preliminary probability analyses of flood defences uncertainty analyses of all issues which are related to flood defences review and development of software codes for reliability calculation applicability of improved methods.Floodsit

Preliminary reliability analysis of flood defences in the pilot site \u92Scheldt\u92

This report describes the flood defence structures of the pilot site River Schelde Estuary and the overall probability of failure of all flood defences in the area. First, the flood prone area is briefly described as follows: ? the flood prone area ? the failures observed in the past ? an overview of all defence structures ? the flood defence structures in detail together with their potential failure modes The report then continues to describe the algorithm how the flood defences are split into various sections. For each section the probability of failure is then calculated using level II and III methods. From this, the overall failure probability Pf is calculated. The overall purpose of this report is to provide a first idea on the failure probability calculations of the flood defences in the pilot site. This information will identify the gaps in knowledge (e.g. failure modes) and incomplete procedures to calculate Pf. Results will be fed into Theme 1 to improve understanding and knowledge where identified necessary. Calculations have been made by DHV Consultancy and Engineering (Amersfoort, NL) and TU Delft with checks by VNK (Ministry of Water Management, Delft, NL) and assessments by WZE (Waterboard, Zeeland, NL).Floodsit

Reliability Analysis of Flood Sea Defence Structures and Systems

Risk identification consists of defining the hazard, loss causing event E, probability P(E) of that event, perception Pe(E,P(E)) and consequences C(Pe) of that perception. Risk identification is followed by risk management, whose purpose is to mitigate the risks, for example by reducing P(E) or C(Pe) and providing suitable risk communication to the population at risk. Task 7 has focused in this approach for the safety issues of flood defences on the failure probability P(E). It has been subdivided into 4 activities, which are: - preliminary probability analyses of flood defences - uncertainty analyses of all issues which are related to flood defences - review and development of software codes for reliability calculation - applicability of improved methods --- The defence reliability analysis has been developed in this task to support a range of decisions and adopt different levels of complexity (feasibility, preliminary and detailed design). Each tier in the analysis of the reliability of the defence and defence system demands different levels of data on the condition and form of the defence and its exposure to load, but also different types of models from simple to complex. As a result each level will be capable of resolving increasing complex limit state functions. During the project, these levels has been considered and complexity of models and amount of data has been adjusted accordingly.Floodsit

Statistical methods for the risk-based design of civil structures

Civil Engineering and Geoscience

Reliability Analysis of Flood Sea Defence Structures and Systems (Appendices)

Risk identification consists of defining the hazard, loss causing event E, probability P(E) of that event, perception Pe(E,P(E)) and consequences C(Pe) of that perception. Risk identification is followed by risk management, whose purpose is to mitigate the risks, for example by reducing P(E) or C(Pe) and providing suitable risk communication to the population at risk. Task 7 has focused in this approach for the safety issues of flood defences on the failure probability P(E). It has been subdivided into 4 activities: preliminary probability analyses of flood defences uncertainty analyses of all issues which are related to flood defences review and development of software codes for reliability calculation applicability of improved methods.Floodsit

Application of evidential network to model uncertainty in quantitative risk assessment of Natech accidents

Natech is a technological accident which is triggered by a natural disaster. Increasing frequency of natural disasters along with an increasing growth of industrial plants are bound to increase the risk of Natechs in the future. Due to a lack of accurate field observations and empirical data, risk assessment of Natechs has largely been reliant on experts opinion and thus prone to epistemic uncertainty in addition to aleatory uncertainty originating from randomness of natural disasters. Evidential Network (EN) is a directed acyclic graph based on Dempster-Shafer Theory to explicitly model the propagation of epistemic uncertainty in system safety and reliability assessment. In the present study, we have illustrated an application of EN to handling epistemic uncertainty in risk assessment of flood-induced floatation of storage tanks.Safety and Security Scienc

Investigation of long-term hurricane activity

This paper presents a new approach of applying numerical methods to model storm processes. A storm empirical track technique is utilized to simulate the full tracks of hurricanes, starting with their initial points over the sea and ending with their landfall locations or final dissipations. The theoretical framework was first described in the literature by Vickery et al. (2000) and is extended in this study by introducing a new formula and several substantial adjustments. The results show acceptable accuracy, even if the input data are for a short period. For the Vietnam area, the research successfully generates a large database of synthetic storm tracks on the basis of a limited historical track record and a local climatological variable (i.e. sea surface temperature). The model is evaluated through the comparisons between the key storm statistics derived from the observed and simulated data over the entire research area (i.e. the South China Sea). In addition, some possible applications of this method to coastal structure design and coastal risk assessment are proposed.Hydraulic EngineeringCivil Engineering and Geoscience

Hurricane risk assessment in a long temporal scale

Hydraulic EngineeringCivil Engineering and Geoscience

Application of evidential network to model uncertainty in quantitative risk assessment of Natech accidents

Natech is a technological accident which is triggered by a natural disaster. Increasing frequency of natural disasters along with an increasing growth of industrial plants are bound to increase the risk of Natechs in the future. Due to a lack of accurate field observations and empirical data, risk assessment of Natechs has largely been reliant on experts opinion and thus prone to epistemic uncertainty in addition to aleatory uncertainty originating from randomness of natural disasters. Evidential Network (EN) is a directed acyclic graph based on Dempster-Shafer Theory to explicitly model the propagation of epistemic uncertainty in system safety and reliability assessment. In the present study, we have illustrated an application of EN to handling epistemic uncertainty in risk assessment of flood-induced floatation of storage tanks.Safety and Security Scienc

Collision risk measure for triggering evasive actions of maritime autonomous surface ships

Collision risk assessment is essential for supporting collision avoidance, which is the core of various collision alert/avoidance systems. One main task of the systems is setting off alarms for taking evasive actions. The alarms need to be triggered before the conflict has no collision-free solution. However, most of existing collision risk measures are independent of conflict resolution. That means the collision alert does not indicate that the collision is avoidable or not. This article proposes an improved time-varying collision risk (TCR) measure, bringing in a new measure. The measurement of TCR reflects not only the dangerous level of the approaching ships but also the difficulty of avoiding collisions. By comparing with traditional measures, e.g., Collision Risk Index (CRI), we found that (1) the TCR can distinguish changes of risk that have identical CRI level, (2) the TCR measure offers a reasonable tool to evaluate the collision risk of entire traffic, and (3) it reflects the influence of maneuverability improvement on collision risk. Based on those results, this article reaches two conclusions: the collision risk is monotonically increasing when introducing more ships, and ignorance of ship maneuverability results in an underestimation of collision risk.Safety and Security Scienc