Steel frame
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Steel frame is a building technique with a "
Concept
The
Wide sheets of steel deck can be used to cover the top of the steel frame as a "form" or corrugated mold, below a thick layer of concrete and steel reinforcing bars. Another popular alternative is a floor of precast concrete flooring units with some form of concrete topping. Often in office buildings, the final floor surface is provided by some form of raised flooring system with the void between the walking surface and the structural floor being used for cables and air handling ducts.
The frame needs to be protected from fire because steel softens at high temperature and this can cause the building to partially collapse. In the case of the columns this is usually done by encasing it in some form of fire resistant structure such as masonry, concrete or plasterboard. The beams may be cased in concrete, plasterboard or sprayed with a coating to insulate it from the heat of the fire or it can be protected by a fire-resistant ceiling construction. Asbestos was a popular material for fireproofing steel structures up until the early 1970s, before the health risks of asbestos fibres were fully understood.
The exterior "skin" of the building is anchored to the frame using a variety of
Cold-formed steel frames
Cold-formed steel frames are also known as lightweight steel framing (LSF).
Thin sheets of galvanized steel can be cold formed into steel studs for use as a structural or non-structural building material for both external and partition walls in both residential, commercial and industrial construction projects (pictured). The dimension of the room is established with a horizontal track that is anchored to the floor and ceiling to outline each room. The vertical studs are arranged in the tracks, usually spaced 16 inches (410 mm) apart, and fastened at the top and bottom.
The typical profiles used in residential
Steel mills produce galvanized sheet steel, the base material for the manufacture of cold-formed steel profiles. Sheet steel is then
Steel-framed walls can be designed to offer excellent thermal and acoustic properties – one of the specific considerations when building using cold-formed steel is that thermal bridging can occur across the wall system between the outside environment and interior conditioned space. Thermal bridging can be protected against by installing a layer of externally fixed insulation along the steel framing – typically referred to as a 'thermal break'.
The spacing between studs is typically 16 inches on center for home exterior and interior walls depending on designed loading requirements. In office suites the spacing is 24 inches (610 mm) on center for all walls except for elevator and staircase wells.
Hot-formed steel frames
Hot Formed frames, also known as
The distinctive feature of hot formed frames is their substantial beam thickness and larger dimensions, making them more robust compared to their cold rolled counterparts. This inherent strength makes them particularly well-suited for application in larger structures, as they show minimal deformation when subjected to substantial loads.
While it is true that hot rolled steel members often have a higher initial cost per component when compared to cold rolled steel, their cost-efficiency becomes increasingly evident when used in the construction of larger structures. This is due to the fact that hot rolled steel frames require fewer components to span equivalent distances, leading to economic advantages in bigger projects.
History
The use of steel instead of iron for structural purposes was initially slow. The first iron-framed building, Ditherington Flax Mill, had been built in 1797, but it was not until the development of the Bessemer process in 1855 that steel production was made efficient enough for steel to be a widely used material. Cheap steels, which had high tensile and compressive strengths and good ductility, were available from about 1870, but wrought and cast iron continued to satisfy most of the demand for iron-based building products, due mainly to problems of producing steel from alkaline ores. These problems, caused principally by the presence of phosphorus, were solved by Sidney Gilchrist Thomas in 1879.
It was not until 1880 that an era of construction based on reliable mild steel began. By that date the quality of steels being produced had become reasonably consistent.[4]
The Home Insurance Building, completed in 1885, was the first to use skeleton frame construction, completely removing the load bearing function of its masonry cladding. In this case the iron columns are merely embedded in the walls, and their load carrying capacity appears to be secondary to the capacity of the masonry, particularly for wind loads. In the United States, the first steel framed building was the Rand McNally Building in Chicago, erected in 1890.
The
See also
- Buckling-restrained braced frame (BRBF)
- Curtain wall (architecture)
- Prefabricated buildings
- Steel building
- Structural steel
- Structural robustness
- Tension fabric structure
References
- ^ "Early steel-frame high-rises". 2022.
- ^ "Light Gauge Steel Framing Shop Drawings". October 10, 2022.
- ^ "Hot Rolled Steel Buildings Deep Dive". August 20, 2023.
- ^ "The properties of cast iron, wrought iron and steel" Archived 2014-03-24 at the Wayback Machine
- ^ Jackson, Alistair, A. "The Development of Steel Framed Buildings in Britain 1880–1905", Construction History, Vol. 14 (1998)