Farm - what is it? Building structure

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The most common meaning of the word "farm" is an agricultural enterprise intended for animal husbandry. But now we are not talking about the place of farming. It contains all the information about the probably oldest building structure, which is still relevant in modern life. It has a wide application in construction, especially in the construction of bridges and sports facilities.

A truss is a system consisting of rods, which remains geometrically unchanged when its rigid nodes are replaced by hinged ones. It also includes trussed beams, which are represented by a combination of a two- or three-span uncut beam and spring rod.

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. The construction of bridges, stadiums, hangars, as well as decorative structures such as pavilions, stages, podiums, etc. is not complete without the use of a farm.

Whendesigning the hull of a ship, aircraft, diesel locomotive, the calculation of strength occurs in the same way as the calculation of the load on the farm.

Classification

A truss is a structure consisting of rods that are interconnected at nodes and form a statically unchanged system. Farms can be classified according to many properties.

According to the load capacity of the structure

• Lungs. They use a single-wall section. Light trusses are most often used in industrial construction.
• Heavy. Heavy trusses are used in the construction of tower cranes, sports stadiums, etc. They use rods of a more complex section than in the lungs. As a rule, they consist of two or three parts due to the large estimated length and the load placed on them. Most often, a two-walled section is used with a two-plane nodal conjugation.

Based on common features

• As intended. By purpose, trusses are tower, bridge, crane, roof trusses, supporting structures, etc.
• By type of material. Wood, steel, aluminum, reinforced concrete, etc. - from 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 section, lattice types, types of support structures, as well as types of chords of the truss building structure.

Spatial-based

• Flat. Farms take on the verticalload, because x rods are located in the same plane.
• Spatial. Distribute the load over its entire area. The Dimensional Truss is made up of many flat trusses connected to each other in special ways.

By type

• Virendel beam.
• Warren Farm.
• Pratt Farm.
• Bolman Farm.
• Fink Farm.
• Triangle truss.
• Kingpost.
• Cross-braced truss.
• Grid city structure.
• Truss under the overhead light.

Design Features

Truss classification by design features is quite extensive. Further, each of the features will be discussed in more detail.

Section types

The cross section in the construction truss is made of rolled profiles. It can be in the form:

• Corner (single or double).
• Pipes (round or square).
• Channel.
• Tavra or I-beam.

Belt Types

The outline of the belt can be represented as:

• Trapezoid. Its advantage lies in the fact that this type of belt stiffens the frame assembly, respectively, along with it, the rigidity of the building increases.
• Triangle. This type of belt is used for beam and cantilever systems. It has a lot of disadvantages, such as irrational consumption of metal when distributing the load, the complexity of the support unit, etc.
• Parabolas. This belt is the mostlaborious. Therefore, segment farms are used very rarely.
• Polygon. Polygon farms are used more often than segment farms. Because in them, the fracture in the nodes of the structure is not so noticeable.
• Parallel belts. Most often used to cover industrial buildings. They have an identical scheme of nodes, lattice elements of equal size, and they also have repeatability of elements and details.

Grid Types

There are six typical grill options:

• Triangular.
• Rhombic.
• Sprengel.
• Prossovaya.
• Slanted.
• Semi oblique.

Types of supports

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 support assembly is hinged or rigid. Types of supports:

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

Operation principle

The uniqueness of this design lies in its "invariance" under the influence of external factors. The load on this system is quite large. The farm is a set of triangles combined into one design. The load in them is concentrated at the junction of the nodes, because the rods show their properties better in the process of compression-tension, and not in a fracture. In modern construction, rigid rather than hinged rods are most often used. It follows from this that when one of them is separated from the wholestructures, they will remain in the same position relative to each other.

The principle of calculating trusses by cutting corners

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

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

Main types of farms

Virendel's beam is a system where all its parts form rectangular holes and thus are connected into a rigid frame. By its design, it does not fit the strict term "farms", because. there is no pair of forces in this beam. It was developed by the Belgian engineer Arthur Virendel. But since this design is quite massive, it is rarely seen in modern architecture

• Warren's farm. This is a simplified version of the Pratt-Hove design. It works on the principle of compression-stretching. Most often made of rolled steel.
• Pratt Farm. The patent for this structure belongs to a father and son from Boston. Caleb Pratt and Thomas Wilson were two of the engineers. They used compressed parts vertically and stretched parts horizontally. Therefore, the load is equally well distributed both from above and from below.
• Bolman's farm has a rather complicated and inconvenient design. This structure gained its popularity in the USA due to the political merits of its creator. The inventor spoke eloquently about the farm, even if not everything was true. Bolman was able to promote his invention with the help of the American government, which sometimes forced city planners to use this design when designing bridges. There are quite a few of our compatriots among the holders of construction farm patents, but not a single "Russian" farm has yet been promoted to the masses in such an original way.
• Fink's farm is a simplified version of Bolman's farm. He simply shortened all its elements and thereby made it more efficient. It also bears a resemblance to the Pratt truss design. It differs from it only in the absence of the lower beam.
• Triangle farm. It is also called "Belgian". This is a modern design, which is presented in the form of triangles with sprengels.
• Kingpost is the easiest farm option. It is a pair of supports resting on a vertical beam.
• The lattice city structure was created to replace the huge wooden bridges. It is quite simple in its design. For it, ordinary wooden boards are used, attached to each other at an angle, which, in turn, form a lattice.