Hot-rolled steel and mixed structures
Why this topic is needed
Section titled “Why this topic is needed”Because in reality a structure is rarely pure. In most buildings several materials and technologies work together:
- a thin-walled steel frame in the walls and floors,
- a hot-rolled beam over the large openings,
- concrete in the foundations and sometimes the floor,
- timber where that is the logical choice.
Good design does not cling to one technology but puts each where it is best.
The main questions
Section titled “The main questions”When to use which
Section titled “When to use which”A thin-walled section is economic for small and medium loads with a close frame. A hot-rolled section for long spans and concentrated loads. When HRS is needed alongside LGS.
How they meet
Section titled “How they meet”The connection where the two technologies come together: different material thicknesses, different fixing methods, different tolerances.
What to know about welding
Section titled “What to know about welding”Because hot-rolled steelwork is generally welded — and that brings questions of quality and verification. EN 1090 and execution classes.
How to protect it from corrosion
Section titled “How to protect it from corrosion”Thick steel gets different surface protection from galvanised thin sheet.
Where the two technologies are strongest together
Section titled “Where the two technologies are strongest together”Rooftop additions: the reserve capacity of the existing building is tight, so a light structure is an advantage — but long-span transfer members often have to be hot-rolled. Rooftop additions.
Hall-like spaces: the main frame in hot-rolled steel, the enclosing and infill structure in LGS.
The point
Section titled “The point”The question is not which technology is better but where their boundary lies. A good structure switches where the other solution is more economic.