The Rectangular Steel Hollow Section segmentation by application delineates the primary end‑uses that drive market volume. In the construction sector, rectangular hollow sections are favored for load‑bearing frames, staircases, and façade supports, accounting for roughly 40% of total demand due to large‑scale residential and commercial projects. Infrastructure projects—including bridges, tunnels, and utility structures—contribute about 30%, reflecting government spending on transport and energy networks. The automotive segment, at 15%, utilizes these sections for chassis sub‑structures and protective cages, benefitting from lightweighting trends. Machinery applications, such as industrial equipment frames, represent 10% of the market, while other uses (e.g., agricultural machinery, renewable energy mounts) comprise the remaining 5%. Each application’s share directly influences production capacity, pricing dynamics, and regional growth patterns within the overall market.