In modern construction metal columns are quite often used, which serve as a support for the external and internal parts of the building. It is impossible to do without them, since they form a supporting frame. Steel structures are used more often, because they are characterized by high strength and ease of installation. Some designers use them as decorative elements of buildings or individual rooms.
Compound elements
All metal columns consist of several parts: head, rod and base. The tip is the upper part, which perceives the load from the roof and transfers it to the core. When calculating it, not only the weight of the supporting beams, trusses, but also the features of their fastening are taken into account.
In the middle part of the column is a rod that transfers the load to the base (base). When calculating it, it is important to consider the equidistance of the support, that is, equal flexibility is taken relative to the axes of the section. This principle allows you to save on material and get a stable design. Powerful products must be reinforced with stiffeners.
Base - the foundation of the structure, which transfers the entire load to the foundation. It is also needed to mount the support. When calculating the base, the thickness and area of the supporting part, as well as the foundation material, are taken into account.
Varieties
The material allows you to get different intricate shapes from it, but many metal columns have a cross section in the form of an I-beam, a rectangular or round pipe. Section dimensions are calculated based on strength (usually compression) and stability. The latter characteristic depends on the presence of ties, half-timbered racks, etc.
Depending on the design, the columns can have a constant, step and composite section. The construction of a constant section is a single rod, which is used in frameless buildings, warehouses and hangars. Equipment with a maximum load capacity of 20 tons can be installed on it.
The stepped columns are designed to install equipment with a carrying capacity of more than 20 tons. Thanks to a special section, their bending stiffness is increased and stability is improved. This design has two bearing branches: the main and the crane.
Composite metal columns are rarely used, and can absorb different loads (relative to the axis). They are needed for:
- installation of cranes at a low height;
- installation of cranes in several tiers;
- reconstruction of buildings.
Application area
Steel columns are in great demand due to their low cost, ease of installation, ease of joining, small size. A large number of advantages allows you to use them for the construction of:
- industrial buildings (e.g. workshops);
- civil buildings (multi-storey buildings for various purposes);
- wide-span coatings and bridges.
- buildings requiring special design (the ability to get various architectural and design forms).
Structural Analysis
Before you install metal structures, you need to perform their full calculation. For the construction of a steel frame, monolithic step bases without glasses are most often used. To calculate the design, you need to collect all the loads, as well as determine the number, size of the supports, reinforcement and the depth of laying. In this case, it all depends on the weight of the building and the characteristics of the soil (the denser it is, the less racks will be needed).
The calculation should be performed so that the load from the structure is distributed evenly over the ground. If you have any difficulties with this, then you can prepare a powerful pillow (from sand or gravel). As soon as the bearing capacity of the foundation and the weight of the building are known, the total area of the sole of the foundation is easily calculated. And then the load on each support is calculated.
The foundation for the metal column differs from the usual base in that each element operates separately from the others. They are not interconnected in any way, so design errors can lead to a skew of the entire building.
Foundation device
These bases do not have glasses and are equipped with anchor bolts holding the base of the product. Their top is located so that the bottom of the frame element and the ends of the anchors are covered with a floor. If the installation of columns implies a deepening of the foundation by at least 4 m, then precast reinforced concrete sub-columns can be used. The lower end of this design is fixed in a glass, and the upper edge is equipped with anchors.
For adjacent racks you will need a common base, even if steel and reinforced concrete structures are located nearby. The design position of the frame elements is ensured by the correct installation of anchors, and the accuracy of the alignment in height - by preparing the surface of the bases.
Column Installation
Installation of metal structures should be carried out so that the deviations along the axes are not more than the permitted SNiP (especially applies to milled surfaces). Simple columns are installed as a whole, while heavy columns are assembled from components. To mount, they must be grabbed, lifted, brought to the supports, aligned and secured. To capture structures, slings are used, under which linings are placed (for example, made of wood). Lifting is done by turning or sliding.
There are several ways to support the base on the base (nodes of metal columns can be seen below):
- on its surface without gravy,
- on steel plates with gravy;
- on beams, rails (you will need a gravy of the base with a solution).
In practice, a simpler installation method is used. In this case, the shoes are mounted on welded steel linings, and fastened to the bottom of the columns. As soon as the structures are installed and fixed, they are poured with a solution.
The installation of columns involves careful alignment with the help of geodetic instruments and plumb lines. At the same time, their marks, verticality and position in the plan are checked. Anchor bolts are used for fastening the structures: 2-4 pcs are needed. for columns up to 15 m high. An additional stability will be provided by braces, which are removed after final fixing. Higher elements are additionally reinforced with struts, temporary ties and struts. To obtain a stable frame, it is better to mount the columns together with crane beams.