Questions dealing with Hollow Structural Sections (HSS), also known as tube steel shapes. These can be round, square, or rectangular.
Hollow Structural Section (HSS) or tube steel members are structural steel members created by rolling sheet steel into rectangular, square, or circular profile shapes. These are primarily used in the United States or other countries that follow US conventions.
HSS are used primarily as structural columns, though they also find use as structural beams. Since they are closed sections, they are inherently strong in torsional resistance and also exhibit less tendency to lateral torsional buckling as compared to wide-flange beams (W-shapes).
The details of connections to HSS members is typically complicated due to the inside of the member being inaccessible.