The book deals with the structural analysis of the bracing systems of multi-storey building structures and intends to offer useful tools to both researchers and practicing structural engineers. As a consequence, the material is divided into two
parts: Part I presents the theoretical background and Part II gives worked
A couple of decades ago approximate methods played a very important and normally dominant role in the structural design of large structures as often, because of the lack of computer power, it was not feasible, or practical, or sometimes possible, to carry out an “exact” analysis of big and complex structures. Then more and more powerful computers with more and more sophisticated programs started to become available to wider and wider structural engineering communities. Soon the debate started with questions like “Do we need old-fashioned approximate methods?” and “Should we rely on brainless number-crunching machines that cannot think?” and “Shall we just input all the data, press <Enter> and by tomorrow the structural analysis is done?” and “Computers in the design office: boon or bane” (Smart, 1997). This debate will perhaps go on for a long time. But one thing seems to be certain: simple analytical methods and closed-form approximate solutions do and will play an important role in practical structural engineering and theoretical research (Howson, 2006). Not only because they offer important independent checking possibilities to help to avoid CAD (Computer Aided Disaster) (Brohn, 1996) but also because the development and use of such methods help to understand the complex behaviour of large structures such as multi-storey buildings. They are also useful tools in developing structural engineering common sense and a feel for the behaviour of structures.
When multi-storey buildings are investigated, two main avenues are available for the structural engineer: sophisticated and powerful computer packages can be used or “conventional” calculations can be made. Perhaps the best way to tackle the task is to employ both approaches: at the preliminary design stage simple hand methods can quickly help to establish the main structural dimensions and to point to efficient bracing system arrangements. More detailed computer-based analyses can follow. Before the final decision is made, it is essential to check the results of the computer analysis and recheck the adequacy of the key elements of the bracing system. Here, again, suitable analytical methods can play a very useful part. The fact that the methods in the book are all based on continuous models has another advantage. When the results of a finite element analysis (based on discrete models) are checked, it is advantageous to use a technique that is based on a different approach, i.e., on continuous media.
Part II presents sixteen examples worked out to the smallest details, with step-by-step instructions. The examples range from the deflection or frequency or stability analysis of individual bracing units to the complex deflection and frequency and stability analyses of bracing systems, considering both planar and spatial behaviour. Although most of the formulae in the book are of the back-ofthe- envelope type, due to the complexity of global three-dimensional analyses, some of the calculations may still seem to be rather cumbersome to carry out by hand. It is very rare, however, that a structural engineer today would wish to do actual hand-calculations, however simple they may be. Convenient spreadsheets and calculation worksheets make it possible to do the structural analysis and document its result at the same time in minutes. All the methods presented in the book are suitable for this type of application; in fact the worksheet version of all the sixteen worked examples has been prepared and made available for download. These one-to-eight page long worksheets cover a very wide range of practical application and can also be used as templates for other similar structural engineering situations.