This book delves into the cutting-edge field of lightweight high-performance steel–concrete composites, tailored for research and applications in marine structures. Such marine structures may be subjected to static sustained heavy loads, dynamic ice-contact pressure, ship impact, and other demanding conditions, which require lightweight design, high resilience, and superior durability. Through an intricate fusion of experimental, numerical, and analytical methods, it provides a comprehensive understanding of the material and structural behavior of these composites under various loading scenarios, including flexural and shear response under dynamic impact and punching loads. The content covers the development of lightweight high-ductility cement composites, lightweight rubberized cement composites, and sustainable LC³-based ultra-lightweight cement composites, as well as mild steel/stainless steel single-/double-layered steel–concrete sandwich composites filled with lightweight high-ductility cementitious materials. Furthermore, the dynamic behavior of fiber-reinforced ultra-lightweight high-ductility cement composites under high-strain-rate compression and tension is examined to reveal the material’s failure mechanisms, alongside providing numerical modeling and data-driven predictions of the dynamic increase factor. The structural performance of sandwich wall, beam, and shell elements under marine-relevant loading conditions—including flexural, punching shear, beam shear, compression, combined compression-bending, impact, multi-impact, and residual resistance—is comprehensively investigated. Additionally, the load-transfer mechanism of novel double-layer steel–concrete sandwich composites under various loading conditions (static, impact, repeated impact, etc.) is revealed. Analytical methodologies, numerical studies, and design approaches are provided for practical application. A new type of slotted perforated plate connector for steel–concrete sandwich composites
