In modern construction, metal columns are often used, which serve as a support for the external and internal parts of the building. You can’t do without them, because they form a supporting frame. Steel structures are used more often, because they are distinguished by high strength and ease of installation. Some designers use them as decorative elements of buildings or individual rooms.
Composition elements
All metal columns consist of several parts: head, rod and base. Head - the upper part that takes the load from the roof and transfers it to the rod. 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 there is a rod that transfers the load to the base (base). When calculating it, it is important to take into account the uniform stability of the support, that is, equalflexibility 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 base of the structure, which transfers the entire load to the foundation. It is also needed for mounting the support. When calculating the base, the thickness and area of \u200b\u200bthe supporting part, as well as the foundation material are taken into account.
Varieties
The material allows you to get different intricate shapes from it, however, many metal columns have a section in the form of an I-beam, rectangular or round pipe. Section dimensions are calculated by calculating strength (usually compressive) and stability. The last characteristic depends on the presence of connections, half-timbered racks, etc.
Depending on the design solution, the columns can have a constant, stepped and composite section. The structure of 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.
Stepped columns are designed for installation of equipment with a lifting capacity of more than 20 tons. Due to the 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 take different loads (relative to the axis). They are needed for:
- installation of cranes at a low height;
- installation of cranes in sever altiers;- reconstruction of buildings.
Scope of application
Steel columns are in great demand due to their low cost, ease of installation, ease of docking, small size. A large number of advantages allows them to be used for the construction of:
- industrial buildings (for example, workshops);
- civil buildings (multi-storey buildings for various purposes);
- large-span coatings and bridges. - buildings that require special design (the ability to get different architectural and design forms).
Calculation of structures
Before you install metal structures, you need to perform their full calculation. For the construction of a steel frame, monolithic stepped bases without glasses are most often used. To calculate the structure, you will need to collect all the loads, as well as determine the number, size of supports, reinforcement and depth. In this case, it all depends on the weight of the building and the characteristics of the soil (the denser it is, the fewer racks will be needed).
The calculation should be carried out so that the load from the structure is distributed evenly over the ground. If there are difficulties with this, then you can prepare a powerful pillow (made of sand or gravel). Once the bearing capacity of the base and the weight of the building are known, the total footprint of the base is easily calculated. And then the load on each support is calculated.
The foundation for a metal column differs from the usual foundation in that each element worksapart from others. They are not connected in any way, so design errors can lead to the distortion of the entire building.
Building foundations
These bases do not have cups 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 by the floor. If the installation of columns involves a foundation deepening of at least 4 m, then precast concrete pillars can be used. The lower end of this design is fixed in a glass, and the upper edge is equipped with anchors.
Adjacent racks will need a common base, even if there are steel and reinforced concrete structures nearby. The design position of the frame elements is ensured by the correct installation of anchors, and the accuracy of placement in height is ensured by the preparation of the base surface.
Installation of columns
Mounting of metal structures should be carried out so that the axial deviations are not more than those permitted by SNiP (especially for milled surfaces). Simple columns are installed as a whole, while heavy ones are assembled from constituent elements. To mount, they must be captured, 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 (the nodes of the metal columns can be seen below):
- on its surface withoutgrout, - on steel plates with grout;- on beams, rails (base grout will be required).
In practice, a simpler installation method is used. In this case, the shoes are mounted on steel pads welded together and fastened to the bottom of the columns. As soon as the structures are installed and fixed, they are poured with mortar.
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 to fasten structures: you will need 2-4 pcs. for columns up to 15 m high. Additional stability will be provided by braces, which are removed after final fixing. Higher elements are additionally reinforced with spacers, temporary ties and struts. To obtain a stable frame, it is better to mount the columns together with the crane beams.
