Shell And Spatial Structures Computational Aspects

In recent years powerful engineering workstations for a reasonable price become a valuable tool for the design of complicated constructions such as shell and spatial structures. This availability causes an increasing use of advanced numerical techniques for the static and dynamic analysis of these structures, also in the non-linear range. The I.A.S.S. Working Group nO 13 concerned with "Numerical Methods in Shell and Spatial Structures" and the Department of Civil Engineering of the Katholieke Universiteit Leuven have taken the initiative to organise an International Symposium, providing a forum for discussion and exchange of views between researchers, specialists in numerical analysis on one hand and designers, practising engineer ings on the other hand. These Proceedings contain the papers presented at the Symposium, held in Leuven, July 14-16 1986. The papers are organised in five sections 1. Shell structures 2. Spatial structures 3. Dynamic analysis 4. Non-linear analysis 5. Presentation and interpretation of results The papers covering more than one domain are classified following the main subject. We hope that researchers as well as practising engineers will find a lot of useful information in the book.

This book presents a method which is capable of evaluating the deformation characteristics of thin shell structures A free vibration analysis is chosen as a convenient means of studying the displacement behaviour of the shell, enabling it to deform naturally without imposing any particular loading conditions. The strain-displacement equations for thin shells of arbitrary geometry are developed. These relationships are expressed in general curvilinear coordinates and are formulated entirely in the framework of tensor calculus. The resulting theory is not restricted to shell structures characterized by any particular geometric form, loading or boundary conditions. The complete displacement and strain equations developed by Flugge are approximated by the curvilinear finite difference method and are applied to computing the natural frequencies and mode shapes of general thin shells. This approach enables both the displacement components and geometric properties of the shell to be approximated numerically and accurately. The selection of an appropriate displacement field to approximate the deformation of the shell within each finite difference mesh is discussed in detail. In addition, comparisons are made between the use of second and third-order finite difference interpolation meshes.

Comprehensively introduces linear and nonlinear structural analysis through mesh generation, solid mechanics and a new numerical methodology called c-type finite element method Takes a self-contained approach of including all the essential background materials such as differential geometry, mesh generation, tensor analysis with particular elaboration on rotation tensor, finite element methodology and numerical analysis for a thorough understanding of the topics Presents for the first time in closed form the geometric stiffness, the mass, the gyroscopic damping and the centrifugal stiffness matrices for beams, plates and shells Includes numerous examples and exercises Presents solutions for locking problems

From the preface: Fluid dynamics is an excellent example of how recent advances in computational tools and techniques permit the rapid advance of basic and applied science. The development of computational fluid dynamics (CFD) has opened new areas of research and has significantly supplemented information available from experimental measurements. Scientific computing is directly responsible for such recent developments as the secondary instability theory of transition to turbulence, dynamical systems analyses of routes to chaos, ideas on the geometry of turbulence, direct simulations of turbulence, three-dimensional full-aircraft flow analyses, and so on. We believe that CFD has already achieved a status in the tool-kit of fluid mechanicians equal to that of the classical scientific techniques of mathematical analysis and laboratory experiment.

The aim of this book is to provide a new angle on the analysis of slope stability with the Boundary Element Method. The main advantages of BEM are the reduction of the dimensionality of the problem to be solved and accurate selective calculation of internal stresses. This makes it possible, as shown in the book, to develop the algorithms of slip surface analysis of slope more accurate, more rigorous and more easy to be used than in the conventional limit equilibrium methods. The full elastoplastic analysis of slope is also investigated. Besides, the interested reader can find a detailed study of Melan's fundamental solution such as its displacements, its corresponding Galerkin tensor and the treatment of body forces in the half-plan. The basic theory of BEM is outlined in the book so that undergraduate and graduate students of civil engineering, mining engineering and engineering geology can read it without difficulty.

Tensegrity structures are pre-stressed systems of cables and bars in which no bar is connected to the other and the structure has no continuous rigid skeleton. This general introduction presents an original general method for the design of tensegrity structures, the first configurations of which were found by trial and error. The book begins with two-dimensional tensegrity structures, particularly tensegrity nets, tensegrity chains, tensegrity rings and tensegrity arches. These are then developed to original configurations of spatial tensegrity structures such as tensegrity slabs, primitive spatial tensegrity arches, and primitive tensegrity domes, as well as more elaborate spatial tensegrity structures such as tensegrity cylindrical shells, slim tensegrity domes, tensegrity vaults, and tensegrity caps. Presents a robust new approach to the design of tensegrity structures Extends tensegrity structures to new three-dimensional configurations Tensegrity Structures Design Methods suits structural, civil, and mechanical engineers and architects, as well as graduate students. Oren Vilnay is Professor Emeritus and was founder and head of the Department of Structural Engineering at Ben Gurion University Israel. He is also former head of the Structural Engineering Section at Technion—Israel Institute of Technology. Leon Chernin is Lecturer at the University of Dundee. He was granted a PhD in Structural Engineering from the Technion—Israel Institute of Technology. His research activities encompass both physical testing and numerical modelling. Margi Vilnay is Senior Lecturer at the University of Dundee. She was granted a PhD in Structural Engineering from Heriot-Watt University. She is a chartered member of the Institution of Civil Engineers and the first woman to be elected Vice-Chair of COMEC (Council of Military Education Committees).

This book presents the integrated approach of analysis and optimal design of structures. This approach, which is more convenient than the so-called nested approach, has the difficulty of generating a large optimization problem. To overcome this problem a methodology of decomposition by multilevel is developed. This technique, which is also suitable for implementation on parallel processing computers, has the advantage of reducing the size of the optimization problem generated. The geometric programming for both equality and inequality constraints is used in the optimization.

1. 1 Introduction As offshore oil production moves into deeper water, compliant structural systems are becoming increasingly important. Examples of this type of structure are tension leg platfonns (TLP's), guyed tower platfonns, compliant tower platfonns, and floating production systems. The common feature of these systems, which distinguishes them from conventional jacket platfonns, is that dynamic amplification is minimized by designing the surge and sway natural frequencies to be lower than the predominant frequencies of the wave spectrum. Conventional jacket platfonns, on the other hand, are designed to have high stiffness so that the natural frequencies are higher than the wave frequencies. At deeper water depths, however, it becomes uneconomical to build a platfonn with high enough stiffness. Thus, the switch is made to the other side of the wave spectrum. The low natural frequency of a compliant platfonn is achieved by designing systems which inherently have low stiffness. Consequently, the maximum horizontal excursions of these systems can be quite large. The low natural frequency characteristic of compliant systems creates new analytical challenges for engineers. This is because geometric stiffness and hydrodynamic force nonlinearities can cause significant resonance responses in the surge and sway modes, even though the natural frequencies of these modes are outside the wave spectrum frequencies. High frequency resonance responses in other modes, such as the pitch mode of a TLP, are also possible.