This book is dedicated to the study of an aeroelastic phenomenon of cable-supported long-span bridges known as flutter, and proposes very innovative design methodologies, such as sensitivity analysis and optimization techniques, already utilized successfully in automobile and aerospace industries. The topic of long-span suspension and cable-stayed bridges is currently of great importance. These types of bridge pose great technical difficulties due to their slenderness and often great dimension. Therefore, these bridges tend to have problems caused by natural forces such as wind loads, some of which we have witnessed in our history, and we are currently seeing a very high incidence of bridge construction to overcome geographical obstacles such as bays, straits, or great estuaries. Therefore, it seems very appropriate to write a book showing the current capability of analysis and design, when up until now, the information could only be found partially in technical articles. This book will be useful for bridge design engineers as well as researchers working in the field. This book only requires previous knowledge of structural finite element models and dynamics, and it is advisable to have some previous knowledge in bridge engineering. Nevertheless, this book is very self-contained in such a way that all the information necessary to understand the theoretical developments is presented without the need of additional bibliography.