Analyzed are the merits and demerits of catenary mooring system and taut mooring system, which are commonly used nowadays. As falling somewhere between these two systems, a new mooring system integrating catenary with...Analyzed are the merits and demerits of catenary mooring system and taut mooring system, which are commonly used nowadays. As falling somewhere between these two systems, a new mooring system integrating catenary with taut mooring is proposed. In order to expound and prove the advantages of this new system, the motion performance of a semi-submersible platform is simulated by employing full time domain coupled analysis method. A comparison of the result of new mooting system with that of taut mooring system shows that the movement of the platform using the new type mooting system is smaller than that using the taut mooring system, which ensures a better working condition. Furthermore, the new mooring system is also compatible with the characteristics of catenary mooting system, which eliminates the requirement of anti-uplift capacity of the anchors.展开更多
Precisely predicting the fatigue life of taut-wire mooring systems has become an interesting and important problem for scientists and engineers since there are still difficulties in the inspection and maintenance of m...Precisely predicting the fatigue life of taut-wire mooring systems has become an interesting and important problem for scientists and engineers since there are still difficulties in the inspection and maintenance of mooring lines in a rough sea environment especially in deep waters. In this paper, a comprehensive fatigue analysis is performed for a polyester taut-wire mooring system of an FPSO based on the time domain dynamic theory, rainflow cycle counting method and linear damage accumulation rule of Palmgren-Miner. Three influential factors in the fatigue analysis including the pre-tension, dynamic stiffness and T-N curve are investigated in detail. Two polyester T-N curves, one is from the DNV- 0S-E301 and the other is from the API-RP-2SM, are adopted in the calculation. The fatigue analysis of the mooting system after one-line failure is also carried out. The calculation results indicate that the fatigue life is significantly affected by the T-N curve. The fatigue life decreases with increasing pre-tension, and is largely reduced if taking into account the dynamic stiffness caused by cyclic loading. The analysis also proves that one-line failure has remarkable effects on the fatigue lives of other mooting lines. The present parametric and comparative study is believed to be meaningful to further understanding of the taut-wire mooting system for deepwater applications.展开更多
The slack-taut state of tether is a particular adverse circumstance, which may influence the normal operation state of tension leg platform （TLP）. The dynamic responses of TLP with slack-taut tether are studied with...The slack-taut state of tether is a particular adverse circumstance, which may influence the normal operation state of tension leg platform （TLP）. The dynamic responses of TLP with slack-taut tether are studied with consideration of several nonlinear factors introduced by large amplitude motions. The time histories of stresses of tethers of a typical TLP in slack- taut state are given. In addition, the sensitivities of slack to stiffness and mass are investigated by varying the stiffness of tether and mass of TLP. It is found that slack is sensitive to the mass of TLP. The critical curved surfaces （ over which indicates the slack） for the increase of mass are obtained.展开更多
Mooring system failure can lead to largely different dynamic response of floating structures when compared to the response under the condition of intact mooring system.For a semi-submersible platform with taut mooring...Mooring system failure can lead to largely different dynamic response of floating structures when compared to the response under the condition of intact mooring system.For a semi-submersible platform with taut mooring system under extreme environmental conditions,the typical mooring system failure includes anchor line breaking failure due to the broken anchor line,and the anchor dragging failure caused by the anchor failure in the seabed soil due to the shortage of the anchor bearing capacity.However,study on the mooring failure caused by anchor failure is rare.The current work investigates the effect of three failure modes of taut mooring system on dynamic response of a semi-submersible platform,including one line breaking failure,two lines breaking failure,and one line breaking with one line attached anchor dragging failure.The nonlinear polynomial mooring line model in AQWA was used with integrating the load and displacement curve from the anchor pulling study to characterize the anchor dragging behavior for mooring system failure caused by the anchor failure.The offsets of the platform and the tension of mooring lines were analyzed for mooring system failure with 100-year return period.It is found that the mooring failure of one line breaking with one line attached anchor dragging is a case between the other two mooring failures.The traditional mooring analysis considering only the damaged condition with one line breaking is not safe enough.And the simple way of mooring analysis of two lines breaking is too conservative for the costly offshore engineering.展开更多
The initial boundary value problem of the transverse vibration of a taut string is a classic that can be found in many vibration and acoustics textbooks. It is often used as the basis for derivations of elementary num...The initial boundary value problem of the transverse vibration of a taut string is a classic that can be found in many vibration and acoustics textbooks. It is often used as the basis for derivations of elementary numerical models, for instance finite element or finite difference schemes. The model of axial vibration of a prismatic elastic bar also serves in this capacity, often times side-by-side with the first model. The stored (potential) energy for these two models is derived in the literature in two distinct ways. We find the potential energy in the taut string model to be derived from a second-order expression of the change of the length of the string. This is very different in nature from the corresponding expression for the elastic bar, which is predictably based on the work of the internal forces. The two models are mathematically equivalent in that the equations of one can be obtained from the equations of the other by substitution of symbols such as the primary variable, the resisting force and the coefficient of the stiffness. The solutions also have equivalent meanings, such as propagation of waves and standing waves of free vibration. Consequently, the analogy between the two models can and should be exploited, which the present paper successfully undertakes. The potential energy of deformation of the string was attributed to the seminal work of Morse and Feshbach of 1953. This book was also the source of a misunderstanding as to the correct expression for the density of the energy of deformation. The present paper strives to settle this question.展开更多
Based on communications presented at the international symposium‘West of Japan/East of Europe’,hosted by the Department of Architecture at Xi’an Jiaotong-Liverpool University in concomitance with the exhibit...Based on communications presented at the international symposium‘West of Japan/East of Europe’,hosted by the Department of Architecture at Xi’an Jiaotong-Liverpool University in concomitance with the exhibition‘Bruno Taut’s Hyuga Villa in Atami,Japan’,this text discusses the question of cultural translation in architecture departing from the example of Hyuga Villa,realised by Taut in 1936.Despite the inherently immobile status of architecture,architectural ideas travel widely,as well as their conceivers,the architects.The cultural passage implicit to translation is never flawless,though.Hyuga Villa offers a good case in point,since it was conceived by an architect who had only a partial grasp of local culture and who tried to integrate elements of both Western and Japanese design.But what are the implications of‘translating’architecture?Can we translate not only words but also images,details,building conventions,even aesthetic sensitivities?And is everything translatable?Applied to an artifact recognised today as an important testimony to the encounter between Western and Eastern design cultures,these questions relate to issues that are central to the debate on both architectural history and built heritage,proposing an alternative approach in terms of method and scope.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 51079065)the Science and Technology Support Project Plan of Jiangsu Province (Grant No. BE2010159)A Project Funded by Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Analyzed are the merits and demerits of catenary mooring system and taut mooring system, which are commonly used nowadays. As falling somewhere between these two systems, a new mooring system integrating catenary with taut mooring is proposed. In order to expound and prove the advantages of this new system, the motion performance of a semi-submersible platform is simulated by employing full time domain coupled analysis method. A comparison of the result of new mooting system with that of taut mooring system shows that the movement of the platform using the new type mooting system is smaller than that using the taut mooring system, which ensures a better working condition. Furthermore, the new mooring system is also compatible with the characteristics of catenary mooting system, which eliminates the requirement of anti-uplift capacity of the anchors.
基金supported by the Key Project of the National Natural Science Foundation of China (Grant No. 50639030)the National High Technology Research and Development Program of China (863 Program, Grant No. 2006AA09Z348)
文摘Precisely predicting the fatigue life of taut-wire mooring systems has become an interesting and important problem for scientists and engineers since there are still difficulties in the inspection and maintenance of mooring lines in a rough sea environment especially in deep waters. In this paper, a comprehensive fatigue analysis is performed for a polyester taut-wire mooring system of an FPSO based on the time domain dynamic theory, rainflow cycle counting method and linear damage accumulation rule of Palmgren-Miner. Three influential factors in the fatigue analysis including the pre-tension, dynamic stiffness and T-N curve are investigated in detail. Two polyester T-N curves, one is from the DNV- 0S-E301 and the other is from the API-RP-2SM, are adopted in the calculation. The fatigue analysis of the mooting system after one-line failure is also carried out. The calculation results indicate that the fatigue life is significantly affected by the T-N curve. The fatigue life decreases with increasing pre-tension, and is largely reduced if taking into account the dynamic stiffness caused by cyclic loading. The analysis also proves that one-line failure has remarkable effects on the fatigue lives of other mooting lines. The present parametric and comparative study is believed to be meaningful to further understanding of the taut-wire mooting system for deepwater applications.
基金supported by the National High-Tech Research and Development Program of China(863 Program,Grant No.2006AA09Z350)the National Natural Science Foundation of China(Grant No.10702073)the"Knowledge Innovation Program"of Chinese Academy of Sciences(Grant No.KJCX2-YW-L02)
文摘The slack-taut state of tether is a particular adverse circumstance, which may influence the normal operation state of tension leg platform （TLP）. The dynamic responses of TLP with slack-taut tether are studied with consideration of several nonlinear factors introduced by large amplitude motions. The time histories of stresses of tethers of a typical TLP in slack- taut state are given. In addition, the sensitivities of slack to stiffness and mass are investigated by varying the stiffness of tether and mass of TLP. It is found that slack is sensitive to the mass of TLP. The critical curved surfaces （ over which indicates the slack） for the increase of mass are obtained.
基金financially supported by the National Natural Science Foundation of China(Grant No.51809165).
文摘Mooring system failure can lead to largely different dynamic response of floating structures when compared to the response under the condition of intact mooring system.For a semi-submersible platform with taut mooring system under extreme environmental conditions,the typical mooring system failure includes anchor line breaking failure due to the broken anchor line,and the anchor dragging failure caused by the anchor failure in the seabed soil due to the shortage of the anchor bearing capacity.However,study on the mooring failure caused by anchor failure is rare.The current work investigates the effect of three failure modes of taut mooring system on dynamic response of a semi-submersible platform,including one line breaking failure,two lines breaking failure,and one line breaking with one line attached anchor dragging failure.The nonlinear polynomial mooring line model in AQWA was used with integrating the load and displacement curve from the anchor pulling study to characterize the anchor dragging behavior for mooring system failure caused by the anchor failure.The offsets of the platform and the tension of mooring lines were analyzed for mooring system failure with 100-year return period.It is found that the mooring failure of one line breaking with one line attached anchor dragging is a case between the other two mooring failures.The traditional mooring analysis considering only the damaged condition with one line breaking is not safe enough.And the simple way of mooring analysis of two lines breaking is too conservative for the costly offshore engineering.
文摘The initial boundary value problem of the transverse vibration of a taut string is a classic that can be found in many vibration and acoustics textbooks. It is often used as the basis for derivations of elementary numerical models, for instance finite element or finite difference schemes. The model of axial vibration of a prismatic elastic bar also serves in this capacity, often times side-by-side with the first model. The stored (potential) energy for these two models is derived in the literature in two distinct ways. We find the potential energy in the taut string model to be derived from a second-order expression of the change of the length of the string. This is very different in nature from the corresponding expression for the elastic bar, which is predictably based on the work of the internal forces. The two models are mathematically equivalent in that the equations of one can be obtained from the equations of the other by substitution of symbols such as the primary variable, the resisting force and the coefficient of the stiffness. The solutions also have equivalent meanings, such as propagation of waves and standing waves of free vibration. Consequently, the analogy between the two models can and should be exploited, which the present paper successfully undertakes. The potential energy of deformation of the string was attributed to the seminal work of Morse and Feshbach of 1953. This book was also the source of a misunderstanding as to the correct expression for the density of the energy of deformation. The present paper strives to settle this question.
文摘Based on communications presented at the international symposium‘West of Japan/East of Europe’,hosted by the Department of Architecture at Xi’an Jiaotong-Liverpool University in concomitance with the exhibition‘Bruno Taut’s Hyuga Villa in Atami,Japan’,this text discusses the question of cultural translation in architecture departing from the example of Hyuga Villa,realised by Taut in 1936.Despite the inherently immobile status of architecture,architectural ideas travel widely,as well as their conceivers,the architects.The cultural passage implicit to translation is never flawless,though.Hyuga Villa offers a good case in point,since it was conceived by an architect who had only a partial grasp of local culture and who tried to integrate elements of both Western and Japanese design.But what are the implications of‘translating’architecture?Can we translate not only words but also images,details,building conventions,even aesthetic sensitivities?And is everything translatable?Applied to an artifact recognised today as an important testimony to the encounter between Western and Eastern design cultures,these questions relate to issues that are central to the debate on both architectural history and built heritage,proposing an alternative approach in terms of method and scope.
