A Ring Model for Limit Analysis of Spatial XX Tubular Joints     

Chen Tieyun  Liu Pu  Wang Deyu Professor  Shanghai Jiaotong University  Shanghai . Postdoctor  Shanghai Jiaotong University  Shanghai 《中国海洋工程》1994,(3)

-A ring model is developed to investigate the ultimate strength of tubular X and XX joints in the case that the brace is compressed. In the present analysis, the tubular joint is made of elasto-perfectly-plastic material, and the arch element of the chord section intersecting with the brace is assumed to be rigid. It is found that when 6 plastic hinges for X joint and 8 plastic hinges Tor XX joint appear in the ring, the limit state is reached, and by means of the equivalent ring width Be formula proposed in a previous paper by the authors, the ultimate strength of tubular X and XX joints subjected to compression can be obtained.  相似文献   

Relativistic Information Entropy on Uncertainty Analysis   总被引：1，自引：0，他引：1  

Jin Weiliang Han Jie Professor  Dr. -Eng.  Dept. of Civil Engineering  Zhejiang University  Hangzhou  Lecturer. Dept. of Information Science  Electronic Engineering  Zhejiang University  Hangzhou 《中国海洋工程》1996,(4)

- in this paper, a new approach to relativistic information entropy is used to assess some relative uncertainties in structural reliability assessment. This approach is composed of the information theory and the relativistic theory, and can be used to measure the relativity of parameter uncertainty and system uncertainty in structural reliability theory based on the same generalized relativistic reference system. Therefore, the structural reliability assessment can be assessed reasonably by the approach.  相似文献   

Behavior of Deformation and Strength of Concrete Under Biaxial Stresses     

Song Yupu  Zhao Guofan Associate Professor  Dalian University of Technology  Dalian Professor  Dalian University of Technology  Dalian 《中国海洋工程》1991,(3)

The study of the behavior of concrete under biaxial stresses is essential to the design of offshore concrete platforms. Using the multiaxial test apparatus developed by the authors, the deformation and strength of concrete under biaxial stresses are studied experimentally. Based on the test data, an endochronic damage constitutive model and a failure criterion are proposed. According to the above model, an incremental nonlinear iterative programme is developed, and a plate sample in plane stress state is analyzed.  相似文献   

Offshore Design Waves for Dayaowan Port Area of Dalian Port     

Weng Keqin Guest Associate Professor  Hydraulic  Hydro-Power Engineering Dept.  Tsinghua University  Beijing 《中国海洋工程》1996,(2)

This paper introduces the calculating procedure of the offshore design waves for the Dayaowan port area of Dalian Port. Some suggestions are proposed about the conventional calculating methods with measured waves data.  相似文献   

Effect of Internal Flow on Vortex-Induced Vibration of Submarine Free Spanning Pipelines     

娄敏 丁坚郭海燕  董晓林 《中国海洋工程》2005,19(1):147-154

At present, most researches on the vortex-induced vibration of submarine free spanning pipelines ignore the effect of internal flowing fluid; furthermore, there are no research reports considering the coupling effect of internal and external fluid with the free span. In this paper, combining Iwan‘s wake oscillator model with the differential equation derived for the dynamic response of submarine free spanning pipelines with inclusion of internal flow, the pipe-fluid coupling equations are developed to investigate the effect of internal flow on the vortex-induced vibration of the free spans. The finite dement approximation is implemented to derive the matrix equations of equilibrium. The Newmark method combined with simple iteration is used to solve the system of equations. The results indicate that the internal fluid flow may cause the shift of resonance band to the lower frequency and a slight decrease in the peak value; the effect will be mare pronounced with the increase of the span length and can be weakened in the presence of the axial tension.  相似文献   

Vertical 2D Modeling of Free Surface Flow with Hydrodynamic Pressure Using SIMPLE Arithmetic in σ Coordinates     

吴修广沈永明  郑永红 《中国海洋工程》2004,18(1):79-92

A numerical model for shallow water flow has been developed based on the unsteady Reynolds-averaged Navier-Stokes equations with the hydrodynamic pressure instead of hydrostatic pressure assumption. The equations arc transformed into the a-coordinate system and the eddy viscosity is calculated with the standard k -ε turbulence model. The control volume method is used to discrete the equations, and the boundary conditions at the bed for shallow water models only include vertical diffusion terms expressed with wall functions. And the semi-implicit methed for pressure linked equation arithmetic is adopted to solve the equations. The model is applied to the 2D vertical plane flow of a current over two steep-sided trenches for which experiment data are available for comparison and good agreement is obtained. And the model is used to predicting the flow in a channel with a steep-sided submerged breakwater at the bottom, and the streamline is drawn.  相似文献   

Long-Term Joint Distribution of One-Tenth Large (or Significant) Wave Height with Average Period     

Pan Jinchang Associate Professor  Dalian University of Technology  Dalian 《中国海洋工程》1992,(4)

- In this paper, by using the wave data from a few oceanographic observation stations in the coastal zone of the Yellow Sea, the East China Sea and the South China Sea, the long-term joint distribution of the one-tenth large (or significant) wave height with average period is studied. The statistical data demonstrate that the long- term distribution of the one- tenth wave height or average period fits the log-normal distribution, thus the joint distribution also fits the two-dimensional log-normal distribution. Then the conditional probability distribution of the average period is derived, and the range as well as the mode of the average wave period corresponding to a certain return period of wave height can be calculated easily.  相似文献   

Beta Distribution of Surface Elevation of Random Waves   总被引：2，自引：0，他引：2  

ZHANG  Jun 《中国海洋工程》2001,(1):53-60

A probability density function (PDF) is derived of beta distribution with both λ3 (skewness) and λ4 (kurtosis) as parameters for weakly nonlinear wave surface elevation by use of a method recently proposed by Srokosz. This PDF not only has a simpler form than the well-known Gram-Charlier Series PDF derived by Longuet-Higgins. but also overcomes an obvious shortcoming of the latter that when the series is unsuitably truncated, the resulting PDF is locally negative. To test the derived beta PDF, laboratorial experiments of wind waves are conducted. The experimental data indicate that the theoretical requirements of the parameters in the beta PDF are fulfilled. The experimental results show that the present PDF is in better agreement with the measured data than the beta PDF only including parameter λ3, and also than the Gram-Charlier Series PDF truncated up to the term of H6.  相似文献   

Buckling Propagation in Marine Pipelines     

Lin Zhongqin  Shen Huishen Chen Tieyun Dr. Associate Professor  Dept. of Mechanical Eng.  Shanghai Jiao Tong University  Shanghai Professor  Dept. of Civil Engineering  Shanghai Jiao Tong University  Shanghai Professor  Dept. of Naval Arch  and Ocean Eng.  Shanghai Jiao Tong University  Shanghai 《中国海洋工程》1993,(1)

The buckling propagation in marine pipelines is studied by means of the cylindrical shell model in this paper. Several parameters including geometrical parameter D/ T, L/ D, physical parameter E and σy are discussed. The computed results are compared with the available experimental data and other computed results, it is found that the present results are closer to the experimental results than other computed results.  相似文献   

A Study on Crack Detection with Modal Parameters of A Jacket Platform   总被引：1，自引：0，他引：1  

张兆德  王德禹 《中国海洋工程》2004,18(1):1-10

Crack detection procedures by different modal parameters are analyzed for identitying a crack and its location and magnitude in a jacket plafform. The first ten natural frequencies and modal shapes of the jacket models are obtained by numerical experiments based on NASTRAN Code. A crack at different locations and of different magnitudes is imposed in the model at the underwater beams. Then, the modal evaluation parameters are calculated numerically, to illustrate the evaluation of modal parameter criteria used in jacket crack detection. The sensitivities of different modal parameters to different cracks are analyzed. A new technique is presented for predicting the approximate location of a breakage in the absence of the data of an intact model. This method can be used to detect a crack in underwater menbers by use of incomplete mode shapes of the top members of the jacket.  相似文献