Optimum Design of Steel Structures pdf.

The cost plays an important role in the design of engineering structures. This role can be illustrated by an example. In the design of a crossing over a big river the designer has two possibilities: design a number of small-span bridges with a number of basements or build a large-span bridge with only two basements. The cost comparison helps designers to select the cheaper version since the cost of basements depends on the quality of soil.

In the case of welded structures the cost comparison helps to select the most economic structural version since the welding is an expensive fabrication technology. Our research has been focused on the use of the optimum design methods to minimize the cost of welded structures. This systematic research resulted in optimized structural types using realistic numerical problems.

This book contains studies worked out during last five years and is a continuation of or books published in years 1984, 1997, 2003 and 2008. Studies on beams, tubular trusses, frames, stiffened plates and shells are grouped in separate chapters. Chapter 1 gives a survey on our experiences in the field of structural optimization. Separate chapters deal with the mathematical function minimization methods and the cost calculation.

Our aim is to transfer the results of our research relating to the optimum design of steel structures, the ways to select the most suitable structural versions. This transfer is enabled by abstracts and conclusions of each section.

The following studies on the optimum design for minimum weight or cost can be brought into prominence: Chapter 4: fire design of a welded box beam, Chapter 5: transmission line tower constructed as a welded tubular truss, Chapter 6: earthquake-resistant design of braced frames, Chapter 7: storage tank roof constructed from welded stiffened sectorial plates, Chapter 8: ring-stiffened cylindrical and conical shells.

Structural optimization is a design system for searching better solutions, which better fulfil engineering requirements. The main requirements of a modern loadcarrying structure are the safety, fitness for production and economy. The safety and producibility are guaranteed by design and fabrication constraints, and economy can be achieved by minimization of a cost function. The main aim of this book is to give designers and fabricators aspects for selection of the best structural solution. A lot of structural versions fulfil the design and fabrication constraints and designers should select from these possibilities the best ones. A suitable cost function helps this selection, since a modern structure should be not only safe and fit for production but also economic.

In most cases, treated in this book, much more unknowns should be varied to find the best solution. In these cases one needs special mathematical methods, some of them are treated in this book as well.

The above description shows that the structural optimization has four main components:
(1) design constraints relate to stress, stability, deformation, eigenfrequency, damping,
(2) fabrication constraints formulate the limitation of residual welding distortions, requirements for welding technology, limitations of plate
thicknesses and main structural dimensions, definition of available profile series,
(3) a cost function is formulated according to the fabrication sequence and contains the cost of materials, assembly, welding, cutting and painting, (4) mathematical methods.

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