ISSN  0890-5487 CN 32-1441/P

1996 Vol.(3)

Display Mode:          |     

Dynamic Response Behaviors of Upright Breakwaters Under Breaking Wave Impact
1996, (3): -.
[Abstract](517)
Abstract:
- The dynamic response behaviors of upright breakwaters under broken wave impact are analysed based on the mass-damper-spring dynamic system model. The effects of the mass, damping, stiffness, natural period, and impulse duration (or oscillation period) on the translation, rotation, sliding force, overturning moment, and corresponding dynamic amplifying factors are studied. It is concluded that the ampli-ying factors only depend on the ratio of the system natural period to impulse duration (or oscillation period) under a certain damping ratio. Moreover, the equivalent static approach to breakwater design is also discussed.
Effects of Internal Flow on Vortex-Induced Vibration and Fatigue Life of Submarine Pipelines
1996, (3): -.
[Abstract](346)
Abstract:
- With the rapid development of the offshore oil industries, submarine oil / gas pipelines have been widely used. Under the complicated submarine environmental conditions, the dynamic characteristics of pipelines show some new features due to the existence of both internal and external flows. The paper is intended to investigate the vortex-induced vibration of the suspended pipeline span exposed to submarine steady flow. Especially, the effects of the flow inside the pipeline are taken into account. Its influences on the amplitude of pipeline response, and then on the fatigue life, are given in terms of the velocity of the internal flow.
Influence of Approach Channel on Wave Propagation with Varying Incident Angles
1996, (3): -.
[Abstract](335)
Abstract:
- The variation of the amplitude of waves with varying incident angles when waves propagate through a typical approach channel is discussed by a numerical calculation method, the result of which shows that the influence of the channel on wave propagation is obvious. When the wave propagation direction is in coincidence with the channel axis, the wave amplitude ratio will decrease with the increase of propagation distance. When the incident angle is 15 - 30 , there appears an area of larger wave amplitude ratio on the side slope facing the waves, but at the another side, the wave amplitude ratio is generally small, indicating that the channel has a shielding effect. When waves propagate across the channel perpendicularly, the wave amplitude ratio can be calculated with the shallow water coefficient.
Numerical Simulation and Physical Simulation of Sea Wave Groups
1996, (3): -.
[Abstract](347)
Abstract:
- Based on field wave data, an empirical formula of wave envelope spectrum is given in this paper. Then the methods of both numerical and physical simulation of sea wave groups with the given spectrum and groupiness parameters are suggested.
A Unique Solvable Higher Order BEM for Wave Diffraction and Radiation
1996, (3): -.
[Abstract](369)
Abstract:
- For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a surface-piercing body. The set of over-determined linear equations obtained from the method is modified into a normal set of linear equations by superposing a set of linear equations with zero solutions. Numerical experiments have also been carried out to find the optimum choice of the size of the auxiliary domain and the discretization on it.
A Simple Eddy Viscosity Model of Rough Turbulent Wave Boundary Layer
1996, (3): -.
[Abstract](333)
Abstract:
- A one-layer time-invariant eddy viscosity model is specified to develop a mathematical model for describing the essential features of the turbulent wave boundary layer over a rough bed. The functional form of the eddy viscosity is evaluated based on computational results from a two-equation turbulence model in which the eddy viscosity varies with time and space. The present eddy viscosity model simplifies much of the mathematical complexity in many existing models. Predictions from the present model have been compared with a wide range of experimental data. It is found that the eddy viscosity model adopted in the present study is physically reasonable.
Estimation of Probability of Damage Detection in Offshore Structural Inspection
1996, (3): -.
[Abstract](344)
Abstract:
- To characterize the uncertainty and fuzziness in offshore structural inspection, probability of detection (POD) must be determined. This paper presents the expressions for the POD of four different damage forms mainly existing in offshore structures. The fuzzy-set theory is applied to estimate human errors through the definition of inspection quality. Expressions of inspection quality are achieved. To verify the validity and correctness of the expressions, the data from an offshore platform field inspection of evaluation results of human errors affecting inspection quality are used to estimate the parameters of the POD. The results show that the present models can provide basis for further study of ofTshore structural inspection reliability.
Treatment of Hydrodynamic Loading for Random Sea State
1996, (3): -.
[Abstract](355)
Abstract:
- In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea states are analyzed to highlight the implications and relative merits of four salient linearization techniques.
1996, (3): -.
[Abstract](377)
Abstract:
Dynamic Analysis for Structures Isolated with Dampers
1996, (3): -.
[Abstract](328)
Abstract:
- In this paper, mathematical models and dynamic analyses for both SDOF and MDOF structures isolated with dampers are established and performed, and a comprehensive computation method is provided. The shock absorbing effect is illustrated through an example of a two DOF damper-isolated system excited by sinusoidal waves and actual ground acceleration input recorded in earthquakes. It is shown that most of the responses of the structure with dampers reduce greatly near the resonant zone, but acceleration is enlarged in the lower or higher frequency zone; among various parameters, the influence of frictional coefficient n is the most significant, that of damping ratio of the dampers , is the second, and that of stiffness coefficient of the dampers k, is the slightest.

水利部 交通运输部 国家能源局南京水利科学研究院 《中国海洋工程》编辑部 版权所有

Address: 34 Hujuguan, Nanjing 210024, China Pos: 210024 Tel: 025-85829388 E-mail: coe@nhri.cn

Support by Beijing Renhe Information Technology Co. Ltd E-mail: info@rhhz.net

苏ICP备05007122号