The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Roger Chang - One of the best experts on this subject based on the ideXlab platform.
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straight talk about riser Tension and more
ASME 2009 28th International Conference on Ocean Offshore and Arctic Engineering, 2009Co-Authors: Roger ChangAbstract:One of most confusing issues in riser engineering is the riser Tension. The infamous Effective Tension equation relates it to the so-called material Tension with external and internal pressures. Controversy remains after numerous papers published trying to clarify the subject, because different interpretations were presented by different authors. Instead of explaining this ‘abstract’ equation mathematically using the free body diagram and differential equation as done in the literatures, this paper presents a down-to-earth interpretation that follows the riser loading history which starts with the Effective Weight to re-derive the same equation. Four keys to solve the riser Tension mystery are identified; they are the hydrostatic head pressure vs. applied pressure, pressure generates the pressure end cap load vs. none generated, the vertical (top-Tensioned) riser vs. bent (catenary) riser, and the single string riser vs. multiple strings riser. Based on these four keys, this paper will address the difference between the Effective Tension and material Tension and identify which Tension is to be used in the stress calculation. Also presented in the paper is the driver-reactor theory developed to explain the Tension load distribution among riser strings due to Poisson’s effect with the applied pressure.Copyright © 2009 by ASME
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straight talk about riser Tension and more
ASME 2009 28th International Conference on Ocean Offshore and Arctic Engineering, 2009Co-Authors: Roger ChangAbstract:One of most confusing issues in riser engineering is the riser Tension. The infamous Effective Tension equation relates it to the so-called material Tension with external and internal pressures. Controversy remains after numerous papers published trying to clarify the subject, because different interpretations were presented by different authors. Instead of explaining this ‘abstract’ equation mathematically using the free body diagram and differential equation as done in the literatures, this paper presents a down-to-earth interpretation that follows the riser loading history which starts with the Effective Weight to re-derive the same equation. Four keys to solve the riser Tension mystery are identified; they are the hydrostatic head pressure vs. applied pressure, pressure generates the pressure end cap load vs. none generated, the vertical (top-Tensioned) riser vs. bent (catenary) riser, and the single string riser vs. multiple strings riser. Based on these four keys, this paper will address the difference between the Effective Tension and material Tension and identify which Tension is to be used in the stress calculation. Also presented in the paper is the driver-reactor theory developed to explain the Tension load distribution among riser strings due to Poisson’s effect with the applied pressure.Copyright © 2009 by ASME
Yang Tao - One of the best experts on this subject based on the ideXlab platform.
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The Quality Control in Construction of Vertical Prestress Based on Vibration Testing Method for the PC Box Girder Bridge
2013 Fifth International Conference on Measuring Technology and Mechatronics Automation, 2013Co-Authors: Wei Qi-zhi, Yang TaoAbstract:The paper presents all operation procedures of a vibration testing method for Effective Tension in box-girder bridge, as well as its application situation in more than thirty long-span PC box-girder bridges. And all the key points have been succesfully used to control the construction quality of rebar vertical prestress system. Moreover, the succesful practice of using the testing method to enhance quality reveals the reliability of rebar vertical prestress system for long-span PC box-girder bridges.
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Key Techniques in Construction of Vertical Prestress Based on a Vibration Testing Method for Effective Tension in PC Box-girder Bridges
Journal of Hunan City University, 2011Co-Authors: Yang TaoAbstract:The paper presents all operation procedures of a vibration testing method for Effective Tension in box-girder bridge,as well as its application situation in more than thirty long-span PC box-girder bridges,by which it totally summarizes all detailed key points of construction technology for Tension quality.And all the key points have been succesfully used to control the construction quality of rebar vertical prestress system.Moreover,the succesful practice of using the testing method to enhance quality reveals the reliability of rebar vertical prestress system for long-span PC box-girder bridges.
Somchai Chucheepsakul - One of the best experts on this subject based on the ideXlab platform.
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nonlinear free vibrations of marine risers pipes transporting fluid
Ocean Engineering, 2005Co-Authors: Sakdirat Kaewunruen, Julapot Chiravatchradej, Somchai ChucheepsakulAbstract:An investigation emphasizing on nonlinear free vibrations of marine risers/pipes to determine the nonlinear natural frequencies and their corresponding mode shapes is presented in this paper. Based on the virtual work-energy functional of marine risers/pipes, the structural model developed consists of the strain energy due to axial deformation, strain energy due to bending, virtual works due to Effective Tension and external forces, and also the kinetic energy due to both the riser and the internal fluid motions. Nonlinear equations of motion coupled in axial and transverse displacements are derived through the Hamilton's principle. To analyze the nonlinear free vibrational behaviors, the system formulation has been reformed to the eigenvalue problem. The nonlinear fundamental frequencies and the corresponding numerically exact mode shapes are determined by the modified direct iteration technique incorporating with the inverse iteration. The significant influences of the marine riser's parameters studied on its nonlinear phenomena are then illustrated here first. Those parameters demonstrate the nonlinear effects due to the flexural rigidity, top Tensions, internal flow velocities, and static offsets.
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Nonlinear free vibrations of marine risers/pipes transporting fluid
Ocean Engineering, 2005Co-Authors: Sakdirat Kaewunruen, Julapot Chiravatchradej, Somchai ChucheepsakulAbstract:An investigation emphasizing on nonlinear free vibrations of marine risers/pipes to determine the nonlinear natural frequencies and their corresponding mode shapes is presented in this paper. Based on the virtual work-energy functional of marine risers/pipes, the structural model developed consists of the strain energy due to axial deformation, strain energy due to bending, virtual works due to Effective Tension and external forces, and also the kinetic energy due to both the riser and the internal fluid motions. Nonlinear equations of motion coupled in axial and transverse displacements are derived through the Hamilton's principle. To analyze the nonlinear free vibrational behaviors, the system formulation has been reformed to the eigenvalue problem. The nonlinear fundamental frequencies and the corresponding numerically exact mode shapes are determined by the modified direct iteration technique incorporating with the inverse iteration. The significant influences of the marine riser's parameters studied on its nonlinear phenomena are then illustrated here first. Those parameters demonstrate the nonlinear effects due to the flexural rigidity, top Tensions, internal flow velocities, and static offsets.
Thierry Villemin - One of the best experts on this subject based on the ideXlab platform.
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Effective Tension shear relationships in exTensional fissure swarms axial rift zone of northeastern iceland
Journal of Structural Geology, 1997Co-Authors: Jacques Angelier, Francoise Bergerat, Olivier Dauteuil, Thierry VilleminAbstract:Abstract The geometry of fracture systems in selected areas of the active Krafla fissure swarm, mid-Atlantic ridge, northeastern Iceland, is analysed. Based on geodetic analysis of the present-day topography at the top of Holocene basaltic lava flows which fill the axial rift zone, the deformation of this initially horizontal surface can be reconstructed. ExTensional deformation is localised at all scales and block tilting, though present, remains minor. Using simple models of the surface expression of normal faults, the geometrical characteristics of the topographic features related to active deformation during tectonic-volcanic events are quantitatively analysed. At crustal depths of about 1 km, normal faults are present and have an average 70 ° dip. Comparison with the dip data of older normal faults observed in the uplifted and eroded shoulders of the rift zone, at palaeodepths of 1–2 km, indicates that this dip determination is valid. Comparisons between the local case study and structural analyses of active fissure swarms on a larger scale suggest that normal faulting plays a major role in the middle section of the thin, newly formed brittle crust of the rift zone. In the axial oceanic rift zone of NE Iceland, the exTensional deformation in the upper crust is dominated by horizontal Tension and shear of normal sense, their relative importance depending on depth. Absolute Tension dominates in the uppermost several hundred metres of the crust, resulting in the development of fissure swarms. Effective Tension plays an important role at a deeper level (2–5 km), because of the presence of magmatic fluid pressure from magma chambers which feed dyke injections. At crustal depths of about 1 km, normal shear prevails along fault planes which dip 60 °–75 °. This importance of normal shear at moderate depth, between upper and lower crustal levels where Tension prevails, is pointed out. Within the exTensional context of rifting, these variations of tectonic behaviour with depth are controlled by both the lithostatic pressure and the Effective Tension induced by the presence of magmatic fluid pressure.
Sakdirat Kaewunruen - One of the best experts on this subject based on the ideXlab platform.
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nonlinear free vibrations of marine risers pipes transporting fluid
Ocean Engineering, 2005Co-Authors: Sakdirat Kaewunruen, Julapot Chiravatchradej, Somchai ChucheepsakulAbstract:An investigation emphasizing on nonlinear free vibrations of marine risers/pipes to determine the nonlinear natural frequencies and their corresponding mode shapes is presented in this paper. Based on the virtual work-energy functional of marine risers/pipes, the structural model developed consists of the strain energy due to axial deformation, strain energy due to bending, virtual works due to Effective Tension and external forces, and also the kinetic energy due to both the riser and the internal fluid motions. Nonlinear equations of motion coupled in axial and transverse displacements are derived through the Hamilton's principle. To analyze the nonlinear free vibrational behaviors, the system formulation has been reformed to the eigenvalue problem. The nonlinear fundamental frequencies and the corresponding numerically exact mode shapes are determined by the modified direct iteration technique incorporating with the inverse iteration. The significant influences of the marine riser's parameters studied on its nonlinear phenomena are then illustrated here first. Those parameters demonstrate the nonlinear effects due to the flexural rigidity, top Tensions, internal flow velocities, and static offsets.
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Nonlinear free vibrations of marine risers/pipes transporting fluid
Ocean Engineering, 2005Co-Authors: Sakdirat Kaewunruen, Julapot Chiravatchradej, Somchai ChucheepsakulAbstract:An investigation emphasizing on nonlinear free vibrations of marine risers/pipes to determine the nonlinear natural frequencies and their corresponding mode shapes is presented in this paper. Based on the virtual work-energy functional of marine risers/pipes, the structural model developed consists of the strain energy due to axial deformation, strain energy due to bending, virtual works due to Effective Tension and external forces, and also the kinetic energy due to both the riser and the internal fluid motions. Nonlinear equations of motion coupled in axial and transverse displacements are derived through the Hamilton's principle. To analyze the nonlinear free vibrational behaviors, the system formulation has been reformed to the eigenvalue problem. The nonlinear fundamental frequencies and the corresponding numerically exact mode shapes are determined by the modified direct iteration technique incorporating with the inverse iteration. The significant influences of the marine riser's parameters studied on its nonlinear phenomena are then illustrated here first. Those parameters demonstrate the nonlinear effects due to the flexural rigidity, top Tensions, internal flow velocities, and static offsets.
