Coupled BEM-FEM Analysis of the Large-Diameter Cylinder Structure System

A method of coupled BEM-FEM analysis for the elastic spatial structure system is presented. It can be applied to the calculation of the stress and deformation of the large-diamater cylinder structure system and it is suitable for symmetric or non-symmetric structures under the distributed or concentrated load. Numerical examples show that the proposed method and computer program BEFEM are quite efficient in the analysis of the large-diameter cylinder structure problems in ocean engineering.     

Three-Dimensional Model Test for Port Engineering with Multi-Directional Waves

-The necessity of using irregular waves, especially multi- directional waves to conduct three-dimensional model tests for port engineering and the test method are described in this paper through an example of model test for a port. The test results show that a deep navigation channel has a large effect on the waves in front of the breakwater near the port entrance and on the wave condition in the port.     

Method to Determine Depositional Range of Sediment Transported from Multiple Sources in Water Area

- The sediment from different sources have different content of the characteristic elements. According to the fuzzy mathematical theory, corresponding calculation and cluster analysis of each sediment sample are carried out, so the main courses of sediment transport in water area can be obtained. The characteristics of sediment from different sources are analysed. It is found that the sediment deposited of certain point in water area is due to the sources' contributions which can be calculated by the formula derived in this paper. Based on the distribution of the contribution values, the depositional range of sediment from each source can be determined. The depositional range in Huangmao Bay is determined as an example.     

Dynamic Response of Fluid-Single Leg Gravity Platform-Soil Interaction System

- An approximate method is presented to investigate the earthquake response of the fluid-single leg (shortened for S. L.) gravity platform-soil interaction system. By assuming a suitable form of the velocity potential of the radiation waves and by using the motion equation and the boundary conditions, the unknown coefficients can be obtained. Thereafter the function of frequency for the interaction system may also be obtained. In this paper, the difference of the system dynamic response between rigid foundation is analyzed and the influences of the various foundation geometric dimension and the various water-depth on the hydrodynamic loading and dynamic response of the system is illustrated.     

Fuzzy Risk Analysis of Harbour Engineering Investment by Hierarchy System Approach

The present risk analysis model of engineering investment is built by fuzzy hierarchy approach under the assumption of maximizing the revenues of the project during its whole life cycle of operation. It can reasonably be expressed by a system evaluation analysis. As a matter of fact, the system, aimed by its system goal can be modelled by a set of factors, constitutively structured by certain links between them, to form a factorial network chart, which represents the essentials of the system behaviours, the nodes of which represent the factors concerned. The weight distribution between factors located at the same level can be determined by the eigen-value problem of a "pair comparison" relation matrix. The weight distribution of factors at each level is successively manipulated until the fuzzy synthetic risk assessment. As an example of risk analysis of engineering investment, a harbour construction project is presented for illustration.     

Influence of Energy Directional Spread on Wave Spectral Refraction

Pierson- Moskowitz Spectrum, JONSWAP Spectrum as well as Bretschneider- Mitsuyasu Spectrum are used in this paper for analyzing the influence of wave energy directional spread on refraction of wave spectrum due to both current and topography of sea bed. The author's calculation indicates that such kind influence on the characteristic value of wave height as well as the average direction of wave energy propagation can not be ignored.     

Hydrodynamic Forces on Inclined Cylinder due to Waves with Crossing Current

Based on Morison's Equation and linear wave theory, hydrodynamic forces acting on inclined cylinders due to waves and crossing current at an angle of a, are analyzed. A method for calculating exciting forces is proposed. Experimental results show that the proposed method in this paper is feasible and can be used in engineering practice.     

A Finite Element Solution of Wave Forces on Submerged Horizontal Circular Cylinders

In this paper, a numerical model is established for estimating the wave forces on a submerged horizontal circular cylinder. For predicting the wave motion, a set of two-dimensional Navier-Stokes equations is solved numerically with a finite element method. In order to track the moving non-linear wave surface boundary, the Navier-Stokes equations are discretized in a moving mesh system. After each computational time step, the mesh is modified according to the changed wave surface boundary. In order to stabilize the numerical procedure, a three-step finite element method is applied in the time integration. The water sloshing in a tank and wave propagation over a submerged bar are simulated for the first time to validate the present model. The computational results agree well with the analytical solution and the experimental data.Finally, the model is applied to the simulation of interaction between waves and a submerged horizontal circular cylinder.The effects of the KC number and the cylinder depth on the wave forces are studied.     

Evalution of Application of p-y Curve Method in Offshore Engineering Foundation

- Based on the Mohr-Coulomb failure principle and Rankine's theory, the laterally loaded pile ultimate resistance formulas of sand and soft clay proposed by Reese and Matlock respectively are discussed in this paper. The authors put forward the modified ultimate resistance formulas on the basis of which the ultimate resistance formula is developed for horizontally loaded pile in multi-layer soil in consideration of the effect of the overburden soil pressure on the calculation of soil layer. It is significant to the correct application of the ultimate resistance formulas in API and ZCS Rules into offshore engineering.     

Experimental Investigation on Durability of Reinforced Concrete Beams in A Simulated Marine Environment

1. IntroductionConcrete is widely used for nearshore and offshore marine structures and bridges (Song et al.,2000; Wang and Song, 2004). Experience has shown that the durability of marine concrete structuresis generally good; however, some cases of serious deterioration also exist due to the lack of durability(Metha and Gerwick, 1982). Under marine conditions, concrete, especially concrete in the splashand tidal zone, is attacked, resulting in corrosion of reinforcing bars. Corrosion of rein…