Light-gauge steel constructions are a special class of building metal structures formed of steel, mainly cold-formed profiles with a thickness of up to 4 mm inclusive, which are widely used in various types of structures. Their scope of use is quite wide — both as secondary elements, such as roofing and wall girders of industrial buildings and as the main load-bearing structures of light steel frames, for example, in residential buildings. They can be used as separate structural elements (for example, floor beams) or combined into more complex frame structures.
1. Scope of LGSF:
· Arrangement of wall enclosing and roofing;
· Erection of low-rise buildings;
· Arrangement of floor and attic decks, erection of partitions;
· Construction, repair and reconstruction of attics, superstructures;
· Creation of prefabricated modular structures;
· Erection of sports, trade, civil, industrial facilities
2. Advantages of the LGSF technology:
· Extensive architectural possibilities
The LGSF frame technology makes it possible to implement complex architectural and design solutions. LGSF-based construction provides freedom of layout, and the possibility to arrange utility lines inside the frame walls and floor decks allows architects to make the most of interior space and create original layouts.
· High speed of construction and possibility to carry out installation regardless of the season
Due to the complete absence of wet processes, LGSF-based frame construction can be carried out regardless of the season. Up to 80% of frame structures are assembled before delivery to the construction site, large components are quickly installed on the construction site.
· Possibility of construction in hard-to-reach places
No heavy lifting equipment is required for the construction of frame building by using the LGSF technology. All elements of the frame are developed in such a way to make their installation possible by efforts of 3-4 people. Ease of assembly, compactness of components and no need for lifting and heavy trucks allow you to carry out construction successfully in a densely developed urban environment and hard-to-reach places.
· Light weight
Galvanized thin-walled profiled metal products have high strength while being very light. Since the metal frame and the whole structure, in general, have a low specific weight, the load on the foundation is significantly reduced. This advantage reduces the cost of foundations.
· Reliability and durability
The durability of galvanized steel guarantees the reliability of the structure of the building frame. The frame made of LGSF is not subject to biological impacts, resists fungi, insects and rodents.
· Fire resistance and fire safety
Frames made of LGSF with typical finishing successfully pass fire tests
· High energy efficiency
Buildings built on the LGSF principle have higher energy efficiency than any other construction technology.
· Environmental friendliness
Steel is a completely safe material and does not have any harmful effects on humans. A frame house is made of environmentally friendly materials. Production and construction generate the minimum amount of unprocessed waste.
· Economic benefits
The use of LGSF-based construction technologies leads to a reduction in the total construction costs, energy saving and long-term maintenance of the building.
3. Forms of cold-formed steel sections
Cold-formed steel elements can be divided into two main types:
1. Linear elements: single profiles and components.
2. Panels and flooring.
3.1 Linear elements can be made of single profiles and components. The scope of use of linear elements is very wide: beams of small spans, roofing or wall joists, free-standing columns or support of wall structures, belts of trusses.
The most frequently produced profiles are Z-profiles (Fig. 1b), U-profiles (Fig. 1e), C-profiles (Fig. 1h), Σ-profiles (Fig. 1i) and Ω-profiles (they are also called hat profiles). (Fig. 1o). The main difference between C- and U-profiles is the presence of bends in the shelves of C-profiles, which makes them more rigid and allows to withstand heavy loads.
3.2 The second type of cold-formed elements are panels and corrugated sheets that can take up evenly distribute loads. As a rule, these profiles are used as roof structures, wall structures and floor structures. The height of a sheet wave is from 20 to 200 mm, and the sheet thickness is from 0.5 to 2.0 mm
Corrugated sheets can be divided into three groups.
The first group includes sheets, the cross section of which consists of rectilinear elements (see the top row in Fig. 3). Such sheets are used in case of minor loads and short spans, as a rule, up to 3 m.
The second group of corrugated sheets includes profiles with longitudinal elements of the rigidity of shelves and walls (see the lower rows in Fig. 3). Such sheets are most widely used as load-bearing sheets and serve as a fixed casing for reinforced concrete joists.
The third group of corrugated sheets includes sheets that have not only longitudinal elements of rigidity but also transverse. Sheets of the third group can be used to cover spans up to 12 meters without the use of girders.
4. Production of cold-formed elements
Cold formed elements are usually produced by using one of two methods:
1. Cold rolling
Structures made by the method of cold rolling (cold-rolled structures) are the most common — it can be both individual elements and roofing and wall decks. These structures are made on special machines from strips of metal rolled into coils up to 900 m long.
5. Design of LGSF
Currently, there are the following regulations for the design of LGSF in Ukraine:
· DSTU-N B V.2.6-87:2009 "Constructions of buildings and structures. Guide for design of buildings with the use of light-gauge steel";
· DSTU-N B EN 1993-1-3 valid until: 2012 Eurocode 3. "Design of steel structures. Part 1-3. General rules. Additional rules for cold-formed elements and corrugated sheets. Amendment No. 1 (EN 1993-1-3: 2006, IDT)"
The following publications were also published under the auspices of the Ukrainian Steel Construction Center Association:
· Calculation of load-bearing and enclosing structures made of cold-formed steel corrugated sheets in accordance with Eurocodes 3
· Calculation of elements made of steel cold-formed corrugated sheets according to Eurocodes 3
· Assortment of cold-formed corrugated sheets for light-gauge steel constructions of Ukrainian manufacturers