Author: Mark Randolph, Mark Cassidy, Susan Gourvenec & Carl Erbrich | Size: 4.2 MB | Format:PDF | Quality:Original preprint | Publisher: Int. Conf. on Soil Mechanics and Geotechnical Engineering (ICSMGE) | Year: 2005 | pages: 54
Design practice in offshore geotechnical engineering grew out of onshore practice, but the two areas have diverged over the last 30 years, driven partly by the scale of the foundation elements used offshore, and partly by fundamental differences in construction techniques.
Groups of many moderate sized piles used onshore are replaced by a few very large diameter piles for offshore applications. Similarly excavation of shallow soft sediments is replaced by the use of deep skirts, transferring the effective foundation depth to the level of the skirt tips, or by forcing footings to penetrate several diameters into the seabed; underwater installation has allowed the use of 'suction' (or underpressure) to aid installation of skirted foundations and caissons.
Emphasis in offshore design is focused more on capacity, paying particular attention to the effects of cyclic loading but generally with less concern on deformations compared with onshore design.
These differences have led to the development of separate design codes for offshore structures, which are in most cases more prescriptive than onshore codes but are also more sophisticated in key areas.
The state of the art report was prepared with colleagues Mark Cassidy and Susan Gourvenec from the University of Western Australia and Carl Erbrich from Advanced Geomechanics in Perth. It describes design principles for foundation and anchoring systems, ranging from shallow footings to piles and caissons, highlighting differences between onshore and offshore practice and also the link (or gap) between research and practice.
It outlines the challenges associated with offshore geotechnics, and reviews current design approaches and research trends for a range of foundation and anchor types.
Shallow foundation systems
In contrast to onshore design, offshore shallow foundations generally incorporate steel or concrete skirts that penetrate through surficial soft soils, forcing any failure surface down to skirt tip level.
Pumping, creating underpressure within the skirted compartments, is generally required to help penetrate the skirts. By subsequently sealing the compartments, the foundation is then able to withstand transient tensile loading, or high applied moments.
Wave loading during design storm conditions typically leads to larger horizontal and moment loading than for onshore structures and hence interaction between vertical, horizontal and moment loading is critical. Rather than the traditional approach of bearing factors accounting for inclination and eccentric of the applied load, three-dimensional failure envelopes in V-M-H space are used in offshore design.
Operation of mobile drilling rigs is still the area with the highest frequency of unpredicted foundation response, both during preloading of the spudcan foundations and during storm conditions.
As these rigs are used in increasing water depths, there is a need for innovative analysis techniques to assess spudcan installation; potential punch through into underlying weaker soil; performance during remobilising in areas where footprints from previous operations exist on the sea floor; and response during eccentric and combined V-M-H loading.
Site characterisation and anchoring systems in deep water Within each offshore region, there has been an inevitable progression from shallow to deep water, with recent installations in 2,000m of water in the Gulf of Mexico and deeper fields being planned.
This has necessitated considerable investment in research to validate new foundation and anchoring systems and also to improve methods for characterising the soil.
Facilities have evolved from fixed steel or concrete platforms, to floating facilities ranging from tension leg platforms with vertical tethers anchored to piles, to SPARs and tankers held in position by catenary mooring chains or, more recently, by lightweight 'taut wire' polyester ropes.
In the soft sediments typically found in deep water, novel 'full flow' penetrometers have been developed to obtain more reliable strength measurements. The average T-bar factor for different sites appears to have a smaller coefficient of variation than the average cone factor, reducing the need to calibrate an appropriate T-bar factor for each site from laboratory tests.
Floating facilities for deep water developments are restrained by mooring systems that may range from vertical tethers, in the case of a tension leg platform, to heavy chains in the form of catenaries that apply predominantly horizontal load to the anchors.
More recently, lightweight polyester ropes provide 'taut wire' mooring systems, where the resulting load on the anchor will lie at 35¦ to 45¦ from the horizontal.
For suction caissons, this angle is such that the failure mode will tend to be vertical, but the potential for a crack to form between the trailing edge of the caisson and the soil is an important consideration.
In ultra deep water, simplicity of installation is at a premium, and novel approaches such as the deep penetrating anchor (DPA) or the simple torpedo anchor become attractive.
Such anchors, typically 10m to 15m long, are allowed to free fall from more than 50m above the seabed and achieve terminal penetration velocities in the vicinity of 30m/s.
This allows the anchor to penetrate to two or three times the length of the anchor, achieving capacities of several MN per anchor. Although such anchors are relatively inefficient in terms of the ratio of holding capacity to weight, this is compensated for by their ease of installation.
ABOUT AUTHOR :
Professor Mark Randolph is director of the ARC-funded Special Research Centre for Offshore Foundation Systems at the University of Western Australia. His research includes many aspects of pile design, but is currently focused on offshore developments in deep water, especially soil characterisation and the estimation of limiting loads for foundation and anchoring systems.
Randolph interacts closely with the offshore industry, particularly through his role as a director of specialist geotechnical consultant, Advanced Geomechanics. He is a fellow of the Australian Academy of Science and of the UK Royal Academy of Engineering and was the 2003 Rankine Lecturer for the British Geotechnical Association. He has recently been awarded a five-year Federation Fellowship by the Australian Research Council.
ABSTRACT :
Design practice in offshore geotechnical engineering grew out of onshore practice, but the two application areas have tended to diverge over the last 30 years, driven partly by the scale of the foundation elements used offshore, and partly by fundamental differences in construction (or installation) techniques. Groups of many moderate-sized piles are replaced by a few very large diameter piles; excavation of shallow soft sediments is replaced by the use of deep skirts, transferring the effective foundation depth to the level of the skirt tips, or by forcing footings to penetrate several diameters into the seabed; underwater installation has allowed the use of ‘suction’ (or under-pressure) to aid installation of skirted foundations and caissons. Emphasis in design is focused more on capacity, paying particular attention to the effects of cyclic loading but generally with less concern on deformations compared with onshore design. These differences have led to the development of separate design codes for offshore structures, which are in most cases more prescriptive than onshore codes but are also more sophisticated in key areas. The paper describes design principles for foundation and anchoring systems ranging from shallow footings to piles and caissons, highlighting differences between onshore and offshore practice and also the link (or gap) between research and practice.
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RAM Elements V8i (SELECTseries 4) 13.0.0.22 1000 days trial
Size: 391 MB
This program provides unequaled flexibility for the design and analysis of different types of 2D or 3D structures containing linear members and shell elements.
The types of analysis available are: First order (Linear Analysis), Second order (P-Delta Analysis) and Dynamic (Seismic Analysis).
In addition, RAM Elements is also capable of designing hot-rolled or cold-formed steel members, wood (sawn lumber and glulam) and reinforced concrete members using the AISC 360-05 ASD, AISC 360-05 LRFD, AISC 360-10 ASD, AISC 360-10 LRFD, AISC 341-05, AISC 341-10, BS 5950-00, AISI 01 ASD, AISI 01 LRFD, AS 4100-98, CSA S16-09, NDS 05 ASD, NDS 05 LRFD, ACI 318-99, ACI 318-05 and BS8110-97 codes respectively. The program includes special modules for designing spread footings, combined footings, reinforced concrete columns, retaining walls, concrete walls, tilt-up walls, masonry walls, continuous beams and trusses.
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IMPORTANT NOTICE: You may use this software for evaluation purposes only.
If you like it, it is strongly suggested you buy it to support the developers.
By any means you may not use this software to make money or use it for commercial purpose.
The book reviews the two features of the variational approach: its use as a universal tool to describe physical phenomena and as a source for qualitative and quantitative methods of studying particular problems.
Berdichevsky’s work differs from other books on the subject in focusing mostly on the physical origin of variational principles as well as establishing their interrelations. For example, the Gibbs principles appear as a consequence of the Einstein formula for thermodynamic fluctuations rather than as the first principles of the theory of thermodynamic equilibrium. Mathematical issues are considered as long as they shed light on the physical outcomes and/or provide a useful technique for the direct study of variational problems. In addition, a thorough account of variational principles discovered in various branches of continuum mechanics is given.
In this book, the first volume, the author covers the variational principles for systems with a finite number of degrees of freedom; the variational principles of thermodynamics; the basics of continuum mechanics; the variational principles for classical models of continuum mechanics, such as elastic and plastic bodies, and ideal and viscous fluids; and direct methods of calculus of variations.
Variational Principles of Continuum Mechanics: II. Applications
This book, the second volume, describes how the variational approach can be applied to constructing models of continuum media, such as the theory of elastic plates; shells and beams; shallow water theory; heterogeneous mixtures; granular materials; and turbulence. It goes on to apply the variational approach to asymptotical analysis of problems with small parameters, such as the derivation of the theory of elastic plates, shells and beams from three-dimensional elasticity theory; and the basics of homogenization theory. A theory of stochastic variational problems is considered in detail too, along with applications to the homogenization of continua with random microstructures.
Both volume in a single 5.5MB rar file
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Author: Leonid P. Lebedev, Michael J. Cloud, Victor A Eremeyev | Size: 2.07 MB | Format:PDF | Quality:Original preprint | Publisher: World Scientific Publishing Company | Year: May 18, 2010 | pages: 373 | ISBN: 9814313122, ISBN-13: 978-9814313124
The tensorial nature of a quantity permits us to formulate transformation rules for its components under a change of basis. These rules are relatively simple and easily grasped by any engineering student familiar with matrix operators in linear algebra. More complex problems arise when one considers the tensor fields that describe continuum bodies. In this case general curvilinear coordinates become necessary. The principal basis of a curvilinear system is constructed as a set of vectors tangent to the coordinate lines. Another basis, called the dual basis, is also constructed in a special manner. The existence of these two bases is responsible for the mysterious covariant and contravariant terminology encountered in tensor discussions.
A tensor field is a tensor-valued function of position in space. The use of tensor fields allows us to present physical laws in a clear, compact form. A byproduct is a set of simple and clear rules for the representation of vector differential operators such as gradient, divergence, and Laplacian in curvilinear coordinate systems.
This book is a clear, concise, and self-contained treatment of tensors, tensor fields, and their applications. The book contains practically all the material on tensors needed for applications. It shows how this material is applied in mechanics, covering the foundations of the linear theories of elasticity and elastic shells.
The main results are all presented in the first four chapters. The remainder of the book shows how one can apply these results to differential geometry and the study of various types of objects in continuum mechanics such as elastic bodies, plates, and shells. Each chapter of this new edition is supplied with exercises and problems most with solutions, hints, or answers to help the reader progress. An extended appendix serves as a handbook-style summary of all important formulas contained in the book.
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Author: Frank M. White | Size: 35.3 MB | Format:PDF | Quality:Scanner | Publisher: McGraw-Hill | Year: January 5, 2005 | pages: 629 | ISBN: 0072402318, ISBN-13: 978-0072402315
Frank White's Viscous Fluid Flow, Third Edition continues to be the market leader in this course area. The text is for a senior graduate level elective in Mechanical Engineering, and has a strong professional and international appeal.
Author Frank White is has a strong reputation in the field, his book is accurate, conceptually strong, and contains excellent problem sets. Many of the problems are new to this third edition; a rarity among senior and graduate level textbooks. The references found in the text have been updated and reflect the most current information available. Users will also be interested to find explanations of, and references to ongoing controversies and trends in this course area.
Topically speaking, the text contains modern information on technological advances, such as Micro- and Nano-technology, Turbulence Modeling, Computational Fluid Dynamics (CFD), and Unsteady Boundary Layers.
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Author: Allan F. Bower | Size: 15.3 MB | Format:PDF | Quality:Original preprint | Publisher: CRC Press | Year: October 5, 2009 | pages: 820 | ISBN: 1439802475, ISBN-13: 978-1439802472
Modern computer simulations make stress analysis easy. As they continue to replace classical mathematical methods of analysis, these software programs require users to have a solid understanding of the fundamental principles on which they are based.
Applied Mechanics of Solids is a powerful tool for understanding how to take advantage of these revolutionary computer advances in the field of solid mechanics. Beginning with a description of the physical and mathematical laws that govern deformation in solids, the text presents modern constitutive equations, as well as analytical and computational methods of stress analysis and fracture mechanics. It also addresses the nonlinear theory of deformable rods, membranes, plates, and shells, and solutions to important boundary and initial value problems in solid mechanics.
The author uses the step-by-step manner of a blackboard lecture to explain problem solving methods, often providing the solution to a problem before its derivation is presented. This format will be useful for practicing engineers and scientists who need a quick review of some aspect of solid mechanics, as well as for instructors and students.
Borrowing from the classical literature on linear elasticity, plasticity, and structural mechanics, this book:
* Introduces concepts, analytical techniques, and numerical methods used to analyze deformation, stress, and failure in materials or components
* Discusses the use of finite element software for stress analysis
* Assesses simple analytical solutions to explain how to set up properly posed boundary and initial-value problems
* Provides an understanding of algorithms implemented in software code
Complemented by the author’s website, which features problem sets and sample code for self study, this book offers a crucial overview of problem solving for solid mechanics. It will help readers make optimal use of commercial finite element programs to achieve the most accurate prediction results possible.
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MATLAB code: PMM,PM,MM interaction curves for short columns of practically any shape
Size: 13 KB
The Matlab code for rectangular column interaction curve I posted last week is actually incorrect. The new one I post now can create the P-M-M, M-M, P-M interaction curves for short columns of practically any arbitrary shapes including openings. It has been extensively checked with spColumn v4.81 lastest version that shows excellent agreement.
4 main srcipt m files are included:
- RcolPMMall_1.m ---> rectangular column
- LcolPMMall_1.m ---> L-shaped column
- CcolPMMall_1.m ---> C-shaped column
- CcolPMMall_1w1O ---> C-shaped column with opening.
For typical regular shapes (rectangle, T, L, C, I, Z, Cross, regular polygons), the global coordinates (Xo,Yo,Xbo,Xbo) of the section & reinf bars can be readily built into the program. For an arbitray shape, they need to be specified.
Other files are supporting functions:
- polygeom.m: calculates area & centriodal coordinates of a polygon (this one I gleaned from the web; the rest are my own's)
- fcutpolygon1.m: cuts a polygon into 2 parts, retains & renumbers one of them for use (this is an essential part used to isolate the concrete compression block) + other minor .m files.
The program produces 4 graphs:
- geometry & reinf patern
- 3D P-M-M surface plot
- 2D Mx-My plot for a specified level of axial force P (that you can change)
- 2D P-M plot for a specified angle (GAMMA)of direction of biaxial bending moment
15 levels of P are used (changeable) ---> for some irregular shapes, the surface plot might look jagged in some places where the contours twist a lot.
Download link for Matlab m files below
Note: for correct results, corner points (Xo,Yo) of arbitary shapes are entered CLOCKWISE for main geometry & COUNTERCLOCKWISE for openings.
global coordinates
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Experimental Studies on Earthquake Response Behavior of Cylindrical Tanks
J. Pressure Vessel Technol. -- February 1987 -- Volume 109, Issue 1, 50 (8 pages)
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Posted by: Sumatra - 09-23-2012, 12:36 PM - Forum: Archive
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Theory and Analysis of Elastic Plates and Shells Author: J.N. Reedy | Size: Unknown MB | Format:PDF | Quality:Unspecified | Publisher: CRC Press | Year: 2006 | pages: 568 | ISBN: 978-0849384158
Because plates and shells are common structural elements in aerospace, automotive, and civil engineering structures, engineers must understand the behavior of such structures through the study of theory and analysis. Compiling this information into a single volume, Theory and Analysis of Elastic Plates and Shells, Second Edition presents a complete, up-to-date, and unified treatment of classical and shear deformation plates and shells, from the basic derivation of theories to analytical and numerical solutions.
Revised and updated, this second edition incorporates new information in most chapters, along with some rearrangement of topics to improve the clarity of the overall presentation. The book presents new material on the theory and analysis of shells, featuring an additional chapter devoted to the topic. The author also includes new sections that address Castigliano's theorems, axisymmetric buckling of circular plates, the relationships between the solutions of classical and shear deformation theories, and the nonlinear finite element analysis of plates. The book provides many illustrations of theories, formulations, and solution methods, resulting in an easy-to-understand presentation of the topics.
Like the previous edition, this book remains a suitable textbook for a course on plates and shells in aerospace, civil, and mechanical engineering curricula and continues to serve as a reference for industrial and academic structural engineers and scientists.
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