Ultimate Strength Analysis of Offshore Jacket Platform

- The ultimate strength analysis of offshore jacket platforms is a research project which has been developed in recent years. With the rapid development of marine oil industry, the departments of design and IMR (Inspection, Maintenance and Repair) in the offshore engineering have attached great importance to this project. The research procedure applies to both the stress check of new design platforms and the whole safety assessment of existing platforms. In this paper, we combine the pseudo non-linear technique with the linear analysis program and successfully analyze the ultimate strength of the space frame structure subject to the concentrated load and a real jacket platform subject to the dead load and environmental load.     

导管架式海洋平台结构极限承载力分析的整体推进法及其软件

根据非线性有限元逐步分析的思想,以已有的结构弹性分析软件为计算核心,提出了一种近似分析结构极限承载力的方法——整体推进法;采用整体推进法,以导管架式海洋平台结构线弹性分析软件ＥＮＳＡ为计算核心,考虑结构构件的损伤影响和维修加固效果,编制了导管架式海洋平台结构极限承载力近似分析软件ＵＡＰ,为导管架式海洋平台结构的安全度评定提供了方法和手段;最后对渤海八号生产／储油平台在１９９３年的状态和ＪＺ２０２ＭＵＱ平台的完好状态进行了极限承载力分析     

Reliability Analysis for Offshore Platform Structural Systems

A system reliability estimation method for spatial jacket platforms is developed in this paper,The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Fi-nite Element Method(FEM).The limit failure states correspond to collapse of a series of structural mem-bers which are identified by engineering design criteria.In this paper the following aspects are taken intoaccount:the punching shear and buckiing failures in member failure modes for the tubular joints and tubu-lar columns respectively;incremental loading approach for establishment of the safety margin equations ofsystem failure;the algorithm of enumerating significant failure modes for the structural systems and otherconcepts,such as the false failure mode and the virtual limit state.The final work is devoted to the reliabili-ty analysis for a practical jacket platform presently put into operation on the Bohai Sea.The computed re-sults shows that method suggested in this paper is feasible and effective for     

Finite Element Analysis of Deformed Legs of Offshore Platform Structures

The element stiffness matrix of the equivalent beam or pipe element of the deformed leg of the platform is derived by the finite element method. The stresses and displacements of some damaged components are calculated, and the numeri-cal solutions agree well with those obtained by the fine mesh finite element method. Finally, as an application of this method, the stresses of some platform structures are calculated and analyzed.     

Aseismic Reliability Analysis Approach for Offshore Jacket Platform Structures

—By means of nonlinear pushover collapse analysis approach,the aseismic reliability analysesof two offshore jacket platforms in the Bohai Gulf in China are studied according to their ocean locationand environmental loadings there.On the basis of those analyses,an aseismic reliability analysis approachis presented.The results show that the aseismic reliability of those platforms is high.Also it is proved thatthis aseismic reliability analysis approach is simple,practical and reliable.     

考虑流固耦合时的海洋平台结构非线性动力分析

采用非线性的Morison方程,建立了考虑流固耦合时的海洋平台非线性动力方程及其时程分析方法.以一固定式导管架平台为算例,计算了考虑流固耦合时的海洋平台浪致振动响应,比较了考虑流固耦合和不考虑流固耦合时海洋平台动力响应的差异.算例表明：在较大的波浪条件下,不考虑流固耦合时的计算结果明显小于考虑流固耦合时的计算结果,因此,偏于不安全.分析认为,在极端海况条件下,考虑流固耦合的分析方法更符合实际情况.     

Optimum Design for Offshore Platform Structural Reliability

In this paper, the main problems concerning reliability design of offshore platform structure are described and the general steps for the use of Safety Coefficient Method are presented.     

基于实测动冰力时程的海洋平台结构冰振反应分析

冰激平台结构振动是影响渤海石油钻采平台冬季正常生产和安全的主要因素。本文采用实测冰压力时程,对渤海辽东湾北部的ＪＺ２０－２ＭＵＱ平台结构进行了冰振反应分析,计算了不同设计冰厚、不同冰作用方向和标高及平台桩腿有无正倒锥体（一种破冰装置）的结构反应,探讨了正倒锥体对减轻冰力和结构反应的作用,发现了结构冰激振动的一些特征,为在该平台上实施振动控制方案提供了依据     

Equivalent Simplifying of Tower Structure and Its Application in Overall Analysis of Offshore Platform

Based on some mechanical principles, this paper presents a new way for simplifying the tower structure on the platform, i. e., substituting the three-dimensional tower structure by using beam elements. For the overall analysis of offshore platform, this method can not only save man- power and computer time, but also get better results. This paper introduces the equivalent-simplifying method and its application in engineering.     

Study on Collision Characters for SPAR Platform

This paper presents the research on the external mechanism of collision characters for a SPAR platform. The collision characters of SPAR platform have not attracted so much attention as that of ships in the past, because short of this kind of collision accidents reported. But with the increasing number of SPAR platforms in the world, the possibility of such kind of accident also increases. Therefore, it is necessary to master the character of SPAR collision. Model test technique is employed to study the external mechanism. The collision scenario is a ship colliding with a SPAR platform moored in the site with 1500 meters water depth. The striking ship hits the SPAR platform on the hard tank near water surface in its longitudinal direction. The specifics of the SPAR＇s motions and the tension forces of the mooring lines are collected to summarize the hydrodynamic characters in the collision scenario. It is found that the maximal displacements and the maximal pitch angles of the SPAR platform, and the maximal tension forces of mooring lines are all linearly proportional to the initial velocity of the striking ship basically. Mooring lines play elastic roles in the collision course.     

冰激振动下海洋平台地基土的动力液化研究

通过动力荷载分析,确定海冰荷载可以引起平台筒边土体液化,并阐述了判别土体液化的方法.利用冰激振动软件以及有限元软件对结构进行动力学分析,得到各筒边土体的最大剪应力.通过室内三轴实验和现场观测结果确定土体物理力学参数,利用判定公式计算得到土体抗液化极限应力.将两者进行对比,可判断筒边土体是否可能发生液化.以渤海某油田筒型基础平台为例,对平台基础土液化安全性进行了判别,证明该方法具有较强的创新性和可行性,对于这一类浅基础平台的地基土液化分析有一定的实践指导作用.     

Perturbation Analysis of the Attached Water Mass Effect on Offshore Platform Dynamic Response

- Theoretically speaking, it is impossible to make the differential equation of motion uncoupled for the natural modes of a system in consideration of the attached water. The hydro-elastic structure is equal to the, non-proportional damping system. In this paper a perturbation analysis method is put forward. The structure motion equation is strictly solved mathematically, and the non-proportional damping problem is transformed into a series of proportional damping ones in the superposition form. The paper also presents the calculation formula of the dyanamic response of the structure being subjected to harmonic and arbitrary load. The convergence of the proposed method is also studied in this paper, and the corresponding convergence conditions are given. Finally, the proposed method is used to analyze the displacement response of a real offshore platform. The calculation results show that this method has the characteristics of high accuracy and fast convergence.     

On the Vibration Reduction Effect of Offshore Platform Vibration Distribution Structure

Based on the Bohai ocean environment characteristics, a new platform vibration distribution structure is designed to reduce the platform vibration due to flowing ice. The effect of the earthquake wave and ocean wave load on this vibration distribution structure is considered in the design. The principal idea of this new vibration distribution structure is dividing the platform main column into the inner tube and the outer tube. The outer tube is connected with the leg pontoon by braces, while the inner tube is used to support the platform deck. The inner tube and outer tube can be connected or disconneted in the region near the water line. For evaluating the vibration reduction effect of such a structure, tests are carried out on a steel model, and the external load of flowing ice, earthquake wave and ocean wave are simulated by concentated random load applied to different points of the model. The tests are performed in water media and air media respectively. The vibration reduction effect is evaluated     

Torsional Response of the Offshore Platform with TMD

It is pointed out in this paper that the offshore platform could be controlled by means of the Tuned Mass Damper (TMD) if there is torsional vibration in the system. The effectiveness of the location of TMD is quantified with the help of the response ratio between the peak responses of the system in the presence and in the absence of TMD. In addition, the parameters of frequency and damping ratio of TMD are optimized.     

Experimental Study on Superficial Sliding of a New Type of Offshore Platform

- In order to verify the theoretical design and computation of a new type of platform, laboratory model test of the superficial sliding of the platform is carried out. Test results show that the requirement for the stability of the platform can be satisfied, and the API-82 criterion can be met. It is also suggested that, in order to enhance the stability of the platform, a buried- pad with porous holes and a long apron-board should be adopted in the design of the new type of platform.     

Dynamic Plastic Analysis of Ship-Platform Collision

This paper studies intensively the problems of ship-platform collision.The ship and platformare treated as one structural system connected with spring elements and then motion equation of the colli-sion system is established.A nonlinear force-displacement relationship is derived for the simulation of lo-cal dent in a hit member and the yield surface of a dented tubular section is developed to consider the re-duction of load carrying capacity of hit members.Large deformations,plasticity and strain-hardening ofthe beam-column element are taken into account by combining the elastic large displacement analysis theo-ry with the plastic node method.The effect of the hydrodynamic forces acting on the platform,the rubberfender the property of the local dent and the buckling behavior of beam-column on collision are analyzed.The numerical simulation of the nonlinear dynamic response is carried out by Wilson θ method with updat-ed Newton-Raphson iteration.And the numerical example of the dynamic response of a offs     

废弃海洋桩基平台拆除工程的进度管理方法研究

废弃海洋桩基平台拆除是一项危险、复杂的系统工程,需要多方面的协调配合,加之海上施工条件恶劣,因此造成施工进度难以把握。文中对拆除工程的内容进行了系统的研究,提出了工程进度计划的编制方法。并在此基础上,采用模糊综合评价的方法,综合考虑多个因素的影响,编制、协调、实施、检测和调整施工进度计划,实现对施工的进度的科学管理。     

Study on Dynamic Characteristics of Hydraulic Pumping Unit on Offshore Platform

A new technology of offshore oil rod pumping production is developed for offshore heavy oil recovery. A new type of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure is designed based on the spatial characteristics of offshore platforms. By combining the strengths of sinusoidal velocity curve and trapezoidal velocity curve, a kinematical model of the acceleration, the velocity and displacement of the pumping unit''s hanging point is established. The results show that the pumping unit has good kinematic characteristics of smooth motion and small dynamic load. The multi-degree-of-freedom dynamic model of the single-well pumping unit is established. The first and second order natural frequencies of the sucker rod string subsystem and the pumping unit subsystem are studied. The results show that the first and the second order natural frequencies among the pumping rod string, pumping unit-platform subsystem and the dynamic excitation have differences over 5 times from each other, indicating that resonance phenomenon will not appear during the operation and the dynamic requirements for field use are met in the system.     

Analysis of Collision Protection for Ocean and Offshore Structures

1 .Introduction Many accidents of ocean and offshore structuresinvolve impact loadings .Some famous ship colli-sion cases arethe Tj rn Bridge (Sweden) ,the West Bridge of the Great Belt Link (Denmark) andtheMaracaibo Bridge (Venezuela) . Most studies usedthe Hertzian contact law(Zukaset al .,1982) tocalculate the impact force and analyze structures subjectedtoimpact loadings .Other alternative meth-ods such as the spring-dashpot and momentumbalance methods utilizedthe coefficient of rest…     

谈浅海油田固定平台应急电站设计

结合埕岛中心二号平台的设计实践,对浅海油田固定平台应急发电机组的选型、布置、辅助系统配置、供电范围等内容进行探讨