This book covers steel construction, addressing fundamental concepts, materials, assemblies, and structural calculations according to current standards (Eurocode 3, CCM97). It outlines the advantages and disadvantages of steel, its mechanical properties, and its manufacturing methods. The book details elastic instability phenomena (buckling, warping, lateral-torsional buckling), assembly methods (bolted, welded), and strength calculations for structures under various loads (bending, tension, compression). Emphasizing safety and steel components' usage limits, this book is an essential guide for engineers and construction professionals.Commander