Which code/specification is the primary design standard for structural steel buildings in the United States?

• A. ASCE 7
• B. AISC 360 (Specification for Structural Steel Buildings)
• C. AWS D1.1
• D. AISC 303

Answer: (B)

Designing structural steel buildings in the United States is guided by the document that prescribes how steel members and connections are sized and checked. The primary design standard for this purpose is the AISC 360 specification, the Specification for Structural Steel Buildings. It provides the rules for designing beams, columns, connections, and detailing, covering the design methods used in practice (LRFD and ASD) and defining the allowable strengths and checks needed to ensure safety and performance. While other documents play important roles—ASCE 7 sets the design loads the structure must resist, AWS D1.1 covers welding requirements, and AISC 303 outlines standard practice and project coordination—they do not serve as the main design method for the members themselves. So, the document that mainly governs the design process for structural steel buildings is AISC 360.