The present book has a scope to discuss in depth all the aspects of the notion of semi-rigidity in steel structural connections that has been introduced into the structural steelwork praxis by Eurocode 3: "Design of Steel Structures, from the fundamental notions till the applications of this theory. The book presents a comprehensive survey of all the relevant topics: the definition of semi-rigid steel structural connections, their classification and their influence to the structural response of sway and non-sway steel frames. The sources of connection compliance, ductility and the application...