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A A Roubos - One of the best experts on this subject based on the ideXlab platform.
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time dependent reliability analysis of service proven Quay walls subject to corrosion induced degradation
Reliability Engineering & System Safety, 2020Co-Authors: A A Roubos, T Schweckendiek, Diego Lorenzo Allaix, Raphael D J M Steenbergen, S N JonkmanAbstract:Abstract The assessment of service-proven Quay walls subject to corrosion-induced degradation is inherently a time-dependent reliability problem. Two major challenges are the modelling of corrosion and taking into account the decrease of epistemic uncertainty throughout the Quay wall's service life. The main objective of this study is to examine the probability of failure, despite successful past performance, when the Quay wall is subject to corrosion and randomly imposed variable loads. The development of the annual failure rate is modelled using crude Monte Carlo and by performing a first-order system reliability analysis. The annual failure rates found for service-proven Quay walls vary over time. For those with successful service histories and subject to low corrosion rates, the highest reliability indices are observed in the first year of the service life, whereas with higher corrosion rates the final year prevails. In general, it seems more practical to evaluate reliability on an annual basis rather than over longer time periods, since the latter will introduce an iterative procedure to determine the wall's remaining lifetime. The key findings of this study can be crucial for the lifetime extension of existing Quay walls, and presumably also for other service-proven geotechnical structures subject to corrosion.
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target reliability indices for existing Quay walls derived on the basis of economic optimisation and human safety requirements
Structure and Infrastructure Engineering, 2020Co-Authors: A A Roubos, K Fischer, Diego Lorenzo Allaix, Raphael D J M Steenbergen, S N JonkmanAbstract:General frameworks for reliability differentiation have evolved over time and are mainly developed for buildings. However, recommendations for the safety of existing Quay walls are lacking. In this study, target reliability indices for assessing existing Quay walls were derived by economic optimisation and by evaluating the requirements concerning human safety. In Quay-wall design, some dominant stochastic design variables are largely time-independent, such as soil and material properties. The influence of time-independent variables on the evolution of the probability of failure was taken into consideration, since this affects the present value of future failure costs and the associated target reliability indices. The target reliability indices obtained for existing Quay walls depend on the consequences of failure and the remaining lifetime. If the failure modes of a Quay wall are governed by time-independent design parameters and the Quay wall has already survived the early service period, the residual probability of failure is lower for an existing Quay wall compared to a new structure. Hence, this should be considered in the determination of target reliability indices. The method to evaluate Quay-wall reliability over time can also be used to assess other civil and geotechnical structures.
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enhancing reliability based assessments of Quay walls
2019Co-Authors: A A RoubosAbstract:In the coming years, thousands of Quay walls will approach the end of their intended fifty-year design lifetime and become part of lifetime extension programmes throughout the world. It is presently unclear how reliable these structures are and whether they are still capable of bearing ship and crane loads. An appropriate assessment of a Quay wall’s reliability is essential to safely and responsibly determining its remaining service life. This thesis demonstrates how Quay wall reliability can be evaluated and what aspects should be taken into consideration.
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relationship between the construction costs and the reliability index of Quay walls
Microelectronics Systems Education, 2019Co-Authors: Robbin Wesstein, O M Heeres, J G De Gijt, A A RoubosAbstract:Structures, such as Quay walls, have to meet a particular level of safety. Consequently, in the Eurocode standards, three reliability classes are distinguished, each corresponding to a target reliability index and set of partial factors. In this study, more insight is acquired into the relationship between the Quay wall's construction costs and the associated reliability index β. It appeared that the marginal costs of safety investments of Quay walls are fairly low and in the same order of magnitude of the uncertainty of the estimate of the construction costs. Hence, it seems that the current reliability classes, as defined in the Eurocode standards, are non-efficient for Quay walls. In addition, this study investigates the influence of the partial factors and three failure mechanisms on the construction costs and the reliability index. It was concluded that for the considered cases, the soil's angle of internal friction strongly influences the construction costs and the β of the Quay wall. Furthermore, it follows that economic optimisation in the probabilistic design of Quay walls is possible by increasing the target reliability index of the failure mechanism 'insufficient passive soil resistance' and decrease the target reliability index of 'yielding of sheet pile profile'.
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target reliability indices for existing Quay walls derived on the basis of the lqi criterion
R.Taerwe L. frangopol d.m.caspeele Life-Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision - Proceedings of the 6th Inte, 2019Co-Authors: A A Roubos, K Fischer, Diego Lorenzo Allaix, Raphael D J M Steenbergen, S N JonkmanAbstract:General frameworks for reliability differentiation have evolved over time and are mainly developed for new buildings. However, recommendations for existing Quay walls are lacking. In this study target reliability indices for assessing existing Quay walls were derived by economic optimisation and by evaluating the Life Quality Index criterion (LQI). In Quay wall design, some dominant stochastic design variables are largely time-independent, such as soil and material properties. The influence of time-independent variables on the development of the probability of failure was taken into consideration in this study, because this affects the present value of future failure costs and the associated target reliability indices. The reliability indices obtained in accordance with the LQI acceptance criterion were a little lower than the target reliability indices derived by economic optimization. The target reliability indices obtained for existing Quay walls depend on the consequences of failure and the remaining service life. If failure modes of a Quay wall are largely time-invariant and already survived the first period of the service life, the residual probability of failure is lower for an existing Quay wall compared to a new Quay wall. Hence, this should be considered in the determination of target reliability indices. The method of approach to assess the development of reliability over time can also be used for evaluating target reliability indices of other civil and geotechnical structures. © 2019 Taylor & Francis Group, London.
S N Jonkman - One of the best experts on this subject based on the ideXlab platform.
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time dependent reliability analysis of service proven Quay walls subject to corrosion induced degradation
Reliability Engineering & System Safety, 2020Co-Authors: A A Roubos, T Schweckendiek, Diego Lorenzo Allaix, Raphael D J M Steenbergen, S N JonkmanAbstract:Abstract The assessment of service-proven Quay walls subject to corrosion-induced degradation is inherently a time-dependent reliability problem. Two major challenges are the modelling of corrosion and taking into account the decrease of epistemic uncertainty throughout the Quay wall's service life. The main objective of this study is to examine the probability of failure, despite successful past performance, when the Quay wall is subject to corrosion and randomly imposed variable loads. The development of the annual failure rate is modelled using crude Monte Carlo and by performing a first-order system reliability analysis. The annual failure rates found for service-proven Quay walls vary over time. For those with successful service histories and subject to low corrosion rates, the highest reliability indices are observed in the first year of the service life, whereas with higher corrosion rates the final year prevails. In general, it seems more practical to evaluate reliability on an annual basis rather than over longer time periods, since the latter will introduce an iterative procedure to determine the wall's remaining lifetime. The key findings of this study can be crucial for the lifetime extension of existing Quay walls, and presumably also for other service-proven geotechnical structures subject to corrosion.
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target reliability indices for existing Quay walls derived on the basis of economic optimisation and human safety requirements
Structure and Infrastructure Engineering, 2020Co-Authors: A A Roubos, K Fischer, Diego Lorenzo Allaix, Raphael D J M Steenbergen, S N JonkmanAbstract:General frameworks for reliability differentiation have evolved over time and are mainly developed for buildings. However, recommendations for the safety of existing Quay walls are lacking. In this study, target reliability indices for assessing existing Quay walls were derived by economic optimisation and by evaluating the requirements concerning human safety. In Quay-wall design, some dominant stochastic design variables are largely time-independent, such as soil and material properties. The influence of time-independent variables on the evolution of the probability of failure was taken into consideration, since this affects the present value of future failure costs and the associated target reliability indices. The target reliability indices obtained for existing Quay walls depend on the consequences of failure and the remaining lifetime. If the failure modes of a Quay wall are governed by time-independent design parameters and the Quay wall has already survived the early service period, the residual probability of failure is lower for an existing Quay wall compared to a new structure. Hence, this should be considered in the determination of target reliability indices. The method to evaluate Quay-wall reliability over time can also be used to assess other civil and geotechnical structures.
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target reliability indices for existing Quay walls derived on the basis of the lqi criterion
R.Taerwe L. frangopol d.m.caspeele Life-Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision - Proceedings of the 6th Inte, 2019Co-Authors: A A Roubos, K Fischer, Diego Lorenzo Allaix, Raphael D J M Steenbergen, S N JonkmanAbstract:General frameworks for reliability differentiation have evolved over time and are mainly developed for new buildings. However, recommendations for existing Quay walls are lacking. In this study target reliability indices for assessing existing Quay walls were derived by economic optimisation and by evaluating the Life Quality Index criterion (LQI). In Quay wall design, some dominant stochastic design variables are largely time-independent, such as soil and material properties. The influence of time-independent variables on the development of the probability of failure was taken into consideration in this study, because this affects the present value of future failure costs and the associated target reliability indices. The reliability indices obtained in accordance with the LQI acceptance criterion were a little lower than the target reliability indices derived by economic optimization. The target reliability indices obtained for existing Quay walls depend on the consequences of failure and the remaining service life. If failure modes of a Quay wall are largely time-invariant and already survived the first period of the service life, the residual probability of failure is lower for an existing Quay wall compared to a new Quay wall. Hence, this should be considered in the determination of target reliability indices. The method of approach to assess the development of reliability over time can also be used for evaluating target reliability indices of other civil and geotechnical structures. © 2019 Taylor & Francis Group, London.
Tomohiro Kameoka - One of the best experts on this subject based on the ideXlab platform.
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finite element analysis of earthquake induced damage to anchored sheet pile Quay walls
Soils and Foundations, 1993Co-Authors: Tomohiro KameokaAbstract:In order to examine the capability of the effective stress model proposed by the authors, a finite element analysis was conducted on the field performance of two Quay walls during an earthquake. The Quay walls are of anchored steel sheet piles. Though the cross sections were similar to each other and the locations were adjacent to each other, one Quay wall suffered serious damage while the other did not. The effective stress model used in the analysis consists of a multiple shear mechanism defined in strain space. The model has the capability to represent essential features in the cyclic behavior of sand such as the effects of rotation of principal stress axis directions. For estimating the model parameters, soils were taken from the site for laboratory tests. The record of the earthquake motion was recovered from the site and digitized for the analysis. Results of the finite element analysis are basically consistent with the observed performance of the Quay walls; the model demonstrates the potential ability to differentiate between serious large deformations (i.e. damage) from negligibly small deformations (i.e. no damage) in similar types of sheet pile Quay walls.
Ali Diabat - One of the best experts on this subject based on the ideXlab platform.
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Quay crane scheduling with vessel stability
Transportation research procedia, 2018Co-Authors: Mohamed Kais Msakni, Mohammed Alsalem, Ghaith Rabadi, Mariam Kotachi, Ali DiabatAbstract:Abstract This paper studies the Quay Crane Scheduling Problem (QCSP) that aims to find an optimized schedule for Quay Cranes (QCs) to load and unload containers onto and off of vessels. The resulting schedule has to satisfy certain technical requirements including crane safety margin and non-crossing constraint as well as vessel stability. We propose a two-stage solution method. In the first stage, we solve the problem without the vessel stability constraint using column generation method, and in the second stage, we adjust the obtained schedule when necessary, so that vessel stability is satisfied. A computational study demonstrates the effectiveness of the proposed method.
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a simulation optimization approach for solving the dual cycling problem in container terminals
Maritime Policy & Management, 2015Co-Authors: Qingcheng Zeng, Ali Diabat, Qian ZhangAbstract:Dual cycling is an operation technique whereby Quay cranes perform loading and unloading operations simultaneously in the same ship bay. In this article, a mixed-integer programming model for Quay crane dual-cycling scheduling is developed. The model considers the stowage plan of outbound containers and the operation sequence of Quay cranes. To solve the model, a heuristic method, called bi-level genetic algorithm, is designed. Meanwhile, a simulation optimization method integrating the intelligent decision mechanism of the optimization algorithm and evaluation function of simulation model is proposed. Numerical experiments indicate that dual cycling can reduce the operation time of Quay cranes compared to the method of scheduling loading and unloading separately. Moreover, the model and algorithms developed in this article can tackle Quay crane dual-cycling problem efficiently.
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a joint Quay crane assignment and scheduling problem formulation solution algorithm and computational results
Optimization Letters, 2015Co-Authors: Effrosyni Theodorou, Ali DiabatAbstract:Quay cranes constitute a significant determinant of container handling efficiency and for this reason the Quay crane assignment problem (QCAP) and the Quay crane scheduling problem (QCSP) have received great attention in research streams. However, these interdependent problems are usually solved sequentially, due to the high complexity of integration, leading to a potentially inefficient utilization of resources. This paper presents a simple approach for the integrated Quay crane assignment and scheduling problem (QCASP), by transforming it into a crane-to-bay assignment problem, and develops a Lagrangian relaxation algorithm to solve it. In order to ensure feasibility, a restoration technique is also developed and this Lagrangian relaxation based heuristic is evaluated as a whole. The choice of constraints to be relaxed is justified and the sub- and master problems are derived. The relaxed problem is solved using the constraint generation method and computational results are conducted in order to evaluate the performance of the Lagrangian heuristic, in terms of computational time, Lagrangian bounds and gaps.
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a lagrangian relaxation approach for solving the integrated Quay crane assignment and scheduling problem
Applied Mathematical Modelling, 2015Co-Authors: Ali DiabatAbstract:Abstract Decisions on the Quay crane assignment problem and the Quay crane scheduling problem are typically made independently. However, the efficiency of container terminals can be increased when these decisions are made simultaneously due to the interrelation between Quay crane assignment and scheduling. A mathematical formulation for the integrated Quay crane assignment and scheduling problem (QCASP) is developed in this paper. Practical considerations are incorporated in the model, such as Quay crane (QC) interference. A Lagrangian relaxation is proposed for the model. Feasible solutions are then obtained from the proposed heuristic. Computational results are provided for the proposed Lagrangian relaxation.
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a multi vessel Quay crane assignment and scheduling problem formulation and heuristic solution approach
Expert Systems With Applications, 2014Co-Authors: Ali Diabat, Itsung TsaiAbstract:This paper presents a new approach to analyze the integrated Quay crane assignment and scheduling problem (QCASP). The problem determines the assignment of Quay cranes to vessels and the sequence of tasks to be processed by each Quay crane simultaneously, and accounts for important considerations such as safety margins between Quay cranes (QCs), ordering conditions and vessel priority. Furthermore, QCs can travel from one vessel to another vessel whenever tasks are complete. The integrated problem is difficult to solve with exact methods due to its complexity. Therefore, a genetic algorithm (GA) is proposed to solve the integrated QCASP. Computational results validate the performance of the proposed GA.
Yasin Moradi - One of the best experts on this subject based on the ideXlab platform.
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incremental dynamic analysis of sheet pile Quay walls in order to reach performance based design criteria for this type of wharf
International Journal of Research, 2012Co-Authors: Reza Dezvareh, Khosrow Bargi, Yasin MoradiAbstract:Recent marine structure design codes i.e. PIANC and OCDI suggest performance based design (PBD) of various marine structures including Quays. As well, current study concerns modern dynamic analysis technique of Sheet Pile Quay-walls, hoping for its contribution to assessment of Quay performance criteria. Current study began with modeling of a conventional sheet pile Quay-wall followed by dynamic analysis concerning soil-structure interaction and assessing the IDA curves and summarizing the results and in the end, Mean annual frequency (MAF) investigated.
