Rational application of hot finished rectangular hollow sections in steel structures

Steel hollow sections are manufactured as both welded and seamless elements. The influence of manufacturing technology causes tubes made from the same carbon-manganese steel to differ significantly in terms of their mechanical properties. The cold-formed welded tubes are produced from a steel strip that is roll formed and welded; both technological processes take place at room temperature. This profile type is characterised by less favourable mechanical properties and by much higher inhomogeneity within the cross-section than the seamless tube. However, due to the lower cost of manufacturing, welded tubes are much more often used in building structures than seamless ones. After thermomechanical treatment, the welded tubes, which are referred to as “hot finished”, have almost the same mechanical properties as seamless tubes. However, hot finished sections are more expensive than welded ones; therefore if they are to be applied in the structure in a reasonable way, higher unit cost should translate into an appropriate increase of the load bearing capacity. The aim of the paper is to indicate the application areas of hot finished rectangular hollow sections in which their use is economically justified