Dinh Quang Cuong
Ha Noi University of Civil Engineering, 55 Giai Phong Str, Ha Noi,

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Wave Hydrodynamics across Steep Platform Reefs: A Laboratory Study Dinh Quang Cuong; Thieu Quang Tuan
Civil Engineering Journal Vol 8, No 8 (2022): August
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2022-08-08-015

Abstract

This paper presents a laboratory study on wave transmission across steep platform reefs, aiming at furthering knowledge of wave hydrodynamics and establishing empirical formulations of spectral wave parameters across the reef flat. The ultimate aim of this study is to determine the design wave load to design fixed offshore structures on coral reefs flat. The process of wave transmission across the underground coral strip with a large front slope has been studied on a physical model in the wave trough with nearly 300 experimental cases combined from 05 underground band models and many random wave scenarios and scenarios at different submerged depths. Experimental results show that the abrupt transition in depth from deep water ahead to relatively shallow water in the reef is responsible for the difference in the wave at the top of the strip compared to the wave on the normal beach, especially regarding the statistical distribution of the wave height. Breaking waves at the abrupt transition have deviated the wave height distribution curve from the deep-water (Rayleigh) theoretical distributions and even the existing shallow-water distributions, including the effect of breaking waves. Two sets of empirical formulations of the spectral wave parameters (Hm0 and Tm-1, 0) are eventually derived for the surf zone and the region behind the surf zone, respectively. These local wave parameters can be used as inputs to a wave height distribution model for determining other design characteristic wave heights on steep platform reefs. Doi: 10.28991/CEJ-2022-08-08-015 Full Text: PDF
Assessment of Dynamic Effects of Wave Loads in Fatigue Analysis for Fixed Steel Offshore Structures Dinh Quang Cuong; Bui The Anh
Civil Engineering Journal Vol 9, No 2 (2023): February
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2023-09-02-016

Abstract

This paper presents an algorithm and develops a formula to evaluate the dynamic effect of wave loading on fixed steel offshore structures (jacket structures) through the fatigue damage ratio. Applying the algorithm and formula proposed in this paper to evaluate the dynamic effect of wave loads in fatigue analysis for 03 Jacket structures built at increasing water depth under one specific marine condition and provide specific recommendations on the limits of application of quasi-static and dynamic methods in the fatigue analysis of the jacket structures. This research is really necessary because currently, the current standards (API, DnV) only stop at evaluating the dynamic effects of wave loads acting on the Jacket structure in the strength analysis. These standards propose a limit for quasi-static or dynamic analysis based on the "3.0 s or 2.5 s rule" (use the quasi-static method when Tmax≤ 3.0 s or ≤ 2.5 s), and it is advised that they only apply to waters within the North Sea and the Gulf of Mexico. This paper has demonstrated that it is not appropriate to use the specified standards for the North Sea and the Gulf of Mexico to select the method of fatigue analysis of the jacket structure in marine conditions outside the study area of the standard. Hoped that this paper will be a reference for engineers when choosing a fatigue analysis method for jacket structures in specific marine conditions at the location where the jacket structure has been installed. Doi: 10.28991/CEJ-2023-09-02-016 Full Text: PDF