Steel structures for buildings mainly fall into two categories. For multi-story and high-rise buildings, frame systems (max 6 stories/24m) and braced frame systems (max 12 stories/50m) are common, consisting of columns, beams and bracing. For taller buildings, a composite structure of steel frames and concrete core tubes is adopted to combine steel’s high strength with concrete’s high stiffness. Gabled steel structures include light and heavy frames, which resist planar forces and rely on column braces, horizontal braces and rigid tie rods for stability. With simple force transmission and efficient steel utilization, they are widely used in construction.