Pre-engineered steel buildings are designed and fabricated off-site using standardized structural components. They are lighter and more economical than conventional construction. The key components include tapered steel columns, rafters, purlins, girts, and sheet metal panels. Structural analysis and design are performed to calculate loads and optimize the frame based on factors like wind speed and seismic zone. Components are then erected on-site by connecting prefabricated pieces together using bolted joints.