This paper deconstructs the inherent defects of "steel-clad wood" formwork due to stiffness mismatch and internal electrochemical corrosion from the perspective of fundamental engineering physics. It quantitatively compares the mechanical boundaries of aluminum alloy (elastic modulus ~70 GPa) and structural steel (elastic modulus ~210 GPa) under high fluid lateral pressure. Simultaneously, it systematically analyzes the cost-effectiveness of general-purpose Q235 carbon steel, the optimization of section modulus of Q700 high-strength steel under extreme heavy loads, and the microscopic mechanism of "cut self-healing" of a 1.5mm ZAM (zinc-aluminum-magnesium) coating in strongly alkaline concrete environments through electrochemical sacrificial anodes. This provides global EPC contractors with quantitative decision-making basis for life-cycle cost (LCC).