Stability Evaluation of Rear-Parapet Caisson Breakwaters under Regular Waves by Numerical Simulation

Lee, Byeong Wook; Park, Woo-Sun; Ahn, Suk-Jin

doi:10.9765/kscoe.2020.32.2.95

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…In the majority of reliability-based design studies conducted in Korea, this approach has been maintained, albeit with slight modifications: the safety factor is divided into load and resistance coefficients. Despite the numerous potential applications for reliability-based design, its application in Korea remains somewhat limited 1 – 4 . The limited application of reliability-based design in Korea can be attributed to a lack of comprehensive efforts to integrate the diverse characteristics of the Korean marine environment into the design process 3 , 5 , 6 .…”

Section: Introductionmentioning

confidence: 99%

“…Even more concerning is the treatment of these two forces as mutually independent random processes, which contradicts our physical intuition. In the current reliability-based design platform in Korea, wave and lift forces are modeled as the forces exerted by a design wave with return periods of 50 or 100 years adjusted by bias coefficients 1 – 4 . These bias coefficients, introduced to address the overshooting problem of Goda pressure formula, are assumed to follow their own Gaussian distribution 14 .…”

Section: Introductionmentioning

confidence: 99%

“…Such an approach helps distinguish between different design alternatives, ultimately providing a robust foundation for designing the target structure 16 , 17 . In recent years, most studies related to reliability-based design in Korea have concentrated on reverse engineering of the load and resistance coefficients of vertical-type breakwaters already in service 1 , 2 , 4 . In these studies, authors typically begin their studies by conducting reliability analyses to identify the design point.…”

Section: Introductionmentioning

confidence: 99%

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Reliability-based design optimization for a vertical-type breakwater with multiple limit-state equations under Korean marine environments varying from sea to sea

Cho

2024

Sci Rep

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In this study, as part of basic research aimed at enhancing the accuracy of load and resistance coefficients to ensure their suitability for practical design and promoting the application of underutilized reliability-based design in Korea, the author conducts optimal design based on the reliability analysis of a vertical-type breakwater in the seas off of Haeundae, Yeosu, Mokpo, Gunsan, and Incheon—representative ports in Korea. In doing so, the author utilized the double-loop approach, which simultaneously addresses a reliability problem nested within an optimization process, employing the Polak–He optimization algorithm. To mitigate the substantial numerical effort required by the double-loop approach based on the Polak–He optimization algorithm, which necessitates the gradients of both cost and constraint functions, the subset simulation method was employed. In this process, the author deliberately refrained from using design waves of a specific return period and linear probabilistic models such as the Gaussian distribution, especially concerning wave and lift forces, often viewed as barriers to the widespread application of reliability-based design in Korea. Instead, the author focused on characterizing the uncertainties associated with the wave force, lift force, and overturning moment—variables that significantly impact the integrity of vertical-type breakwaters—by developing probabilistic models for these random variables directly from long-term in situ wave data. These models capture the varied characteristics of the Korean marine environment from sea to sea. In this way, the need for additional assumptions concerning the interrelationship between significant wave and maximum wave heights, along with the wave period, can be eliminated. Following Occam's razor principle, which suggests that explanations constructed with the smallest possible set of assumptions are superior, the reliability-based design optimization of a vertical-type breakwater presented in this study demonstrates promise in terms of simplicity and practicality. The limit state of the vertical-type breakwater was defined to encompass sliding, overturning, and collapse failures, and the strong interrelations between the wave force, lift force, and overturning moment were described using the Nataf joint distribution. As anticipated, simulation results show that solely considering sliding failure, as in the current reliability-based design platform in Korea, leads to an underestimated failure probability. Furthermore, ensuring a consistent failure probability for vertical-type breakwaters using design waves with a specific return period, as in past studies, is not feasible. In contrast, this study demonstrated that breakwaters optimally designed to meet the reliability index requirement of β = 3.5–4 consistently maintain a target failure probability in all sea areas.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reliability-based design optimization for a vertical-type breakwater with multiple limit-state equations under Korean marine environments varying from sea to sea

Cho

2024

Sci Rep

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Consideration on Ways to Reduce a Edge Pressure at Bottom Plate of Caisson Breakwaters

Park¹,

Lee²

2020

J Korean Soc Coast Ocean Eng

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In this study, ways to reduce the edge pressure at the bottom plate of the caisson breakwater were considered. The water depth, freeboard, design wave height and period, and the location of the center of gravity on the superstructure of the breakwater were selected as key design variables that influence the edge pressure, and analyzed how the edge pressure changes according to the change of this key variables. The pressure distribution formulae suggested in the design standard was applied for the calculation of design wave forces. Based on the wave forces, the required effective self-weight of the superstructure and the minimum width of the caisson were determined to have a safety factor of 1.2 against sliding and overturning. From the results, it was found that the edge pressure rapidly increased as the water depth increased, and could exceed the allowable bearing capacity when it reached a certain water depth which is 20 m within the analysis conditions. It was also confirmed that the edge pressure gradually increased linearly as the freeboard increased, but decreased with the increase of the wave height and period. This edge pressure could be significantly reduced up to more than 20% by moving the center of gravity of the superstructure to the seaside, which is 5% of the caisson width. Based on the analysis results and the recently conducted research results, a method was proposed to reduce the edge pressure that can be used in the design.

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Characteristics of Wave Pressures According to the Installation Location of the Caisson Superstructure under Regular Waves

Jun¹,

Lee²,

Kim³

et al. 2022

J Korean Soc Coast Ocean Eng

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In recent years, coastal and port structures have attempted to prevent wave-overtopping or provide waterfront areas by installing superstructures on the structural crowns. In general, in the design stage, the Goda formula acting on the front the structure is applied to calculate the wave pressure acting on the superstructure in consideration of the wave-runup of the design wave. However, the wave pressure exceeding the Goda wave pressure could generate depending on the installation location of the superstructure where the wave-overtopping occurs. This study analyzed the applicability of the Goda formula to the wave pressure calculation for the superstructure of the vertical structures through hydraulic model experiments and numerical simulations. Furthermore, this study investigated the magnitude of the wave pressure acting on the superstructure based on detailed numerical results. As a result, the wave pressure acting on the superstructure was up to 120% higher than the maximum wave pressure on the still water surface. In addition, the wave pressure increases exponentially with the Froude number computed by the overtopping water depth at the crown of the structure, and we proposed an empirical formula for predicting the wave pressure based on the Froude number.

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Stability Evaluation of Rear-Parapet Caisson Breakwaters under Regular Waves by Numerical Simulation

Cited by 3 publications

References 7 publications

Reliability-based design optimization for a vertical-type breakwater with multiple limit-state equations under Korean marine environments varying from sea to sea

Reliability-based design optimization for a vertical-type breakwater with multiple limit-state equations under Korean marine environments varying from sea to sea

Consideration on Ways to Reduce a Edge Pressure at Bottom Plate of Caisson Breakwaters

Characteristics of Wave Pressures According to the Installation Location of the Caisson Superstructure under Regular Waves

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