Structural Analysis

A: The selected section meets the deflection limit with margin while keeping self-weight aligned with the duty. The UC adds stiffness you don't need and drives reactions up into the supports. The smaller UB slips past strength checks but fails service deflection once you run the numbers. The plate girder controls vibration but introduces fabrication and inspection overhead that the duty never asked for.

A: The action confirms whether the altered boundary condition recovers capacity without physical change. Upping the grade shifts yield but leaves Euler buckling untouched. Stress-only checks miss instability entirely once slenderness is high. Corrosion allowance addresses section loss over time, not an immediate load path change.

A: The check shows whether load transfer and plate bending still sit inside limits with the actual thickness. Jumping straight to an NCR skips the engineering decision you're accountable for. Dead load behaviour says nothing about uplift or moment cases. Extra bolt torque can overstress anchors and doesn't thicken steel.

A: The selection targets the loss of section that governs capacity over life in this exposure. Hydrogen effects need high-strength steels and an active CP system. Stress corrosion cracking needs a specific alloy-environment pair that carbon steel doesn't present here. Graphitic attack applies to cast iron, not rolled sections.