Any practitioner who takes his profession in earnest, such that daily work is not a heavy duty but part of their life, will recognize in this book the rigorousness of the analysis and the comprehensive presentation of the problems. This professional attitude is solely able to make the research and design engineer deal with strength structures and their behaviour. Indeed, the computational means that are nowadays available permit the numerical computation of whatever problem; the pro gram libraries are extremely rich and programs themselves have developed intensively. Howeyer, though computers are available at any moment without restrictions on the frequency with which they are employed, they finally impoYerish the creative compe tency of the civil engineer. Thus, he will calculate increasingly more while devising increasingly less. He will draw less and less on the experience gained in devising and implementing bearing structures because the computational process can be repeated as often as desired over a minimum time-period by means of the available programs. \Ve note that nowadays structures are no longer investigated or economically designed to comply with the requirements of the topic of interest. :Much to the contrary, the solutions are chosen so as to comply with the capabilities of the programs. A bearing structure lives as is prescribed by its initial con structive data.