A farm is what? Building construction

The most common meaning of the word "farm" is an agricultural enterprise intended for animal husbandry. But now it's not about the place of farming. Here you can find all the information on probably the oldest building structure, which is still relevant in modern life. It has wide application in construction, especially in the construction of bridges and sports facilities.

A farm is a system consisting of rods that remains geometrically unchanged when its rigid knots are swiveled. It also includes trunnion beams, which are represented by a combination of a two- or three-span uncut beam and girth.

Where is it used?

As already mentioned, the farm in construction is an indispensable element. With its help builders facilitate the construction of the structure and reduce the consumption of necessary materials. Without the use of a farm, construction of bridges, stadiums, hangars, as well as decorative structures such as pavilions, stages, podiums, etc., is not bypassed.

When designing the ship's hull, airplane, or diesel locomotive, the strength calculation is the same way as calculation of the load on the farm.

Classification

A farm is a construction consisting of rods that are linked together at nodes and form a statically unchanged system. Classification of farms can be carried out on a variety of properties.

By load capacity of the structure

• Light . They use a single-section section. Light farms are most often used in industrial construction.
• Heavy . Heavy farms are used in the construction of tower cranes, sports stadiums, etc. They use rods of more complex cross-section than in the lungs. As a rule, they consist of two or three parts because of the large design length and the load imposed on them. Most often use a two-walled section with a two-plane nodal interface.

By common features

• By appointment. By designation of the farm there are tower, bridge, crane, truss farms, supporting structures, etc.
• By type of material. Wood, steel, aluminum, reinforced concrete, etc. - of all this, a construction farm can be made. This is an essential advantage of this system. You can also combine several types of material.
• According to the design features. There are various types of sections, types of lattice, types of supporting structures, as well as types of belts of the construction structure of the farm.

On a spatial basis

• Flat . Farms take on a vertical load, because X rods are located in the same plane.
• Spatial . Distribute the load over its entire area. A spatial truss is formed from a set of flat trusses, united by special methods.

Type

• Beam of Virendel.
• Warren's farm.
• Pratt's farm.
• The Farm of Bolman.
• Fink's farm.
• Triangular truss.
• Kingpost.
• Farm with crossed struts.
• Lattice city structure.
• Farm under the upper light.

Design Features

Classification of the farm on the particular construction is quite extensive. Further, each of the features will be considered in more detail.

Section types

The cross-section in the construction farm is made of rolling profiles. It can be in the form:

• Angle (single or double).
• Pipes (round or square).
• Schweler.
• A brand or an I-beam.

Belt Types

Belt outlines can be represented as:

• Trapezium . Its dignity lies in the fact that this type of belt tightens the frame unit, accordingly, together with it the rigidity of the building also increases.
• The triangle . This type of belt is used for beam and cantilever systems. It has a lot of drawbacks, such as the unreasonable consumption of metal in the distribution of the load, the complexity of the support unit, etc.
• Parabolas . This belt is the most time consuming. Therefore segmented farms are used very rarely.
• The polygon . Polygonal farms are used more often than segmented ones. Because In them a fracture in the nodes of the structure is not so tangible.
• Parallel belts. Most often used to cover industrial buildings. They have an identical circuit of nodes, equal in size lattice elements, they also have the repetition of elements and details.

Types of gratings

There are six typical lattice variants:

• Triangular.
• Orthorhombic.
• Crosswise.
• Cross.
• Raskosaya.
• Half-rattled.

Support types

There are 5 types of supporting structures. In order to select a reference node, you need to know the calculation scheme. It depends on it, whether the supporting node will be hinged or rigid. Types of supports:

• Beam or cantilever.
• Arched.
• Cable-stayed.
• Frame.
• Combined.

Operating principle

The uniqueness of this design is its "immutability" under the influence of external factors. The load on this system is quite large. The farm is a set of triangles united in one construction. The load in them is concentrated in the junction of the nodes; Rods exhibit their properties better in the process of compression-stretching, rather than fracture. In modern construction, a rigid, rather than a hinged connection of rods is most often used. It follows from this that when one of them is separated from the integral structure, they remain in the same position relative to each other.

The principle of calculating trusses by cutting corners

This method of calculating trusses is the simplest. This method is taught in many technical schools.

A farm is a construction, the load on which is concentrated in its nodes. Therefore, you need to calculate all the external factors that will be the load on the nodes. Then - calculate the reaction of the support and find a node in which there are 2 bars with the force applied to them. It is conventionally necessary to separate the rest of the farm and obtain a node in which there will be several known values and 2 unknowns. Then it is necessary to make an equality on two axes and to calculate unknown values. In the same way, the next node is selected, and so on until the farm is calculated.

Basic types of farms

• The Virendel girder is a system where all its parts form rectangular holes and thus merge into a rigid frame. It does not fit the strict term "trusses" in its construction, In this beam there is no pair of forces. It was developed by the Belgian engineer Arthur Wiirendel. But since This design is quite massive, it can rarely be found in modern architecture.

• Warren's farm. This is a simplified version of the Pratt-Hove construction. It works on the principle of compression-stretching. Most often made of rolled steel.
• Pratt's farm. The patent for this structure belongs to the father and son from Boston. Caleb Pratt and Thomas Wilson were two engineers. They used compressed parts vertically, and stretched - horizontally. Therefore, the load is equally well distributed both from above and from below.
• Farm Bolmana has a rather complex and uncomfortable design. Its popularity in the United States this structure was due to the political merits of its creator. The inventor spoke eloquently about the farm, even if not all corresponded to reality. Bolman managed to promote his invention with the help of the US government, which sometimes forced city planners to use this design in the design of bridges. Among the owners of patents for construction farms there are a lot of our compatriots, but not a single "Russian" farm has been promoted to the masses in such an original way.
• Farm Fink is a simplified version of the farm Bolman. He simply truncated all its elements and thereby made it more effective. It also has a similarity to the design of the Pratt farm. It differs from it only by the absence of the lower beam.
• Triangular truss. Also it is called "Belgian". This is a modern design, which is represented in the form of triangles with stitches.
• Kingpost is the simplest version of the farm. It is a pair of supports, supported by a vertical beam.
• The lattice city structure was created to replace the huge wooden bridges. It is quite simple in its construction. It is used for ordinary wooden boards, attached to each other at an angle, which, in turn, form a lattice.