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34v =
3kT
3 • 1,38 • 10-
■4000
179,1 • 10см
= 30,4 — c
Зная выше рассчитанные параметры, возможно определение времени гашения дуги. Оно может быть определено согласно выражению 5. Определение времени гашения дуги
t =
4V
vSn
Где - - объём дугогасительной камеры (определён при обмерке аппарата); 5ос - площадь осаждения ионов (определена при обмерке аппарата), V - скорость ионов; Sос = 3149.3 • 10-6м2; V™ = 1.43 • 10-6м3
t=
4V
4 • 1.43 • 10-
vS0C 30,4 • 10-2 • 3149.3 • 10-
(4) Из проведённого опыта следует, что система
дугогашения работает исправно. Время дугогаше-ния позволяет дуге зажечься ещё раз, но не более. Таким образом можно наблюдать лишь одно повторное зажигание, что удовлетворяет условиям дугогашения.
Список литературы
1. Сахаров П.В. Проектирование электрических аппаратов (Общие вопросы проектирования) 544 с.
2. Залесский А.М. Электрическая дуга отключения. Государственное энергетическое издательство. 1963 - 266 с.
3. Задачник по электрическим аппаратам. Бут-кевич Г.В, Дегтярь В.Г., Сливинская А.Г.
4. Сахаров П.В. Проектирование электрических аппаратов. Учебное пособие для студентов электротехнических вузов. 1971.
= 13.1 мс 5. Брон О.Б. Электрическая дуга в аппаратах
управления государственное энергетическое издательство 1954, 532 с
(4)
FEATURES OF THE CONSTRUCTION OF MONOLITHIC HOUSES
Serdyuchenko V.,
3rd year student of the faculty of architecture and construction
Gorodetsky I.
3rd year student of the faculty of architecture and construction Kuban state agrarian university named after I. T. Trubilin
6
6
Abstract
This article discusses the features of the construction of monolithic houses, their pros and cons, types, technologies and stages of construction. The article also discusses the technology of installing formwork for the construction of monolithic houses and its types. It was found that monolithic houses are more reliable and durable compared to brick houses and can have a different architectural configuration, unlike panel houses.
Keywords: monolith, monolithic house, panel house, brick house, concrete, reinforcement, frame, formwork.
Monolithic construction technology is now actively used in the construction of residential and nonresidential buildings. It is optimally suited for both 1-2-storey cottages and skyscrapers. Very often monolithic houses are chosen by developers of cottage settlements.
A monolithic house is an integral structure [1, p. 32]. When erecting its load-bearing elements, blocks, panels, and bricks are not used, so there are no masonry seams. At the locations of the frame and floors, a form-work is installed, into which concrete is poured. If we are talking about load-bearing structures, they are additionally reinforced. The bars of the reinforcement are placed inside the formwork.
Advantages of building monolithic houses:
- speed of construction - even an impressive multi-storey house can be built in 1 -2 years, and a cottage in just 2-3 months, including the arrangement of the foundation;
- extensive architectural possibilities - thanks to modern formwork, it is possible to fill in any elements of complexity, size and shape [2, p. 46];
- saving costs for the construction of the foundation - in monolithic structures, the load is distributed
evenly to all load - bearing structures, so you can use a lightweight foundation;
- relatively low weight of monolithic structures -the technology is suitable even for construction on sites with heaving or unstable soils, if necessary, piles are installed under the foundation;
- simple redevelopment - during operation, the property can be changed for certain tasks, for example, to divide the premises into separate rooms or, conversely, to combine them, without significantly reducing the load-bearing characteristics of structures:
- long service life - more than 150 years, walls without seams are less destroyed under the influence of the environment;
- high strength and stability - monolithic houses are suitable for regions with high seismic activity, withstand earthquakes up to 8 points;
- increase in useful area - by 10-15% compared to the use of other construction technologies;
- minimal shrinkage - takes no more than 1 month, after which you can immediately lay engineering communications, install windows, doors, perform repairs and put the house into operation;
- saving on the payment of building materials and construction works - a monolithic house is cheaper than a block or brick one, sometimes the difference is up to 30% of the budget without losing the operational characteristics of the property;
- savings in interior and exterior decoration - the walls are initially smooth and even, so they do not need additional alignment.
Disadvantages of monolithic construction:
- The disadvantages of monolithic construction include the inability to perform work in bad weather conditions. For example, if there is excessive humidity in the air, concrete can dry for a long time and get wet in some areas. If the house is built at a temperature below +5 degrees, then the solution is heated with industrial heaters or frost-resistant additives are added to it.
- It is difficult to make gates for concealed installation of engineering communications in an array of reinforced concrete, so their location is provided at the project development stage. Standard monolithic walls need additional insulation. But it is also possible to increase the level of thermal insulation by adding expanded clay to the concrete solution.
There is a difference between a monolithic and a panel house [3, p. 62]. Both the monolithic and panel house is made of concrete. But in the first case, load-bearing structures, walls and ceilings are filled with concrete mortar by means of formwork directly on the site, and in the second case, the structure is assembled from ready - made elements. The minimum number of seams increases not only the strength of the structure, but also its parameters of heat and sound insulation.
Panel houses are mainly built according to standard projects. It is usually impractical to produce individual elements of unusual shapes or sizes at the factory. The use of formwork allows you to build houses in any architectural styles. With its help, you can easily fill columns or arches, which, thanks to reinforcement, will easily withstand any loads.
So which house is better: a monolithic house or a brick one?
Brick houses before the advent of monolithic housing construction technology were always considered the warmest and most reliable. You can build a building with any layout from bricks. But it also has its own limits of strength. Therefore, for houses above 23 floors, the use of brickwork is irrational.
A monolithic private house is not inferior to a brick one in terms of performance characteristics. At the same time, it is more reliable and more durable. The construction of monolithic walls will take 20% less time and will reduce the amount of necessary labor resources, which generally reduces the cost of construction [4, p. 64].
Types of monolithic houses:
- solid monolithic;
- monolithic brick house;
- monolithic frame house.
In monolithic frame houses, the strength of the monolith and the high thermal insulation characteristics of the materials used in frame housing construction are combined.
The technology and stages of construction of such buildings are somewhat different:
1. Arrangement of the foundation. A monolithic slab is poured or a ready-made reinforced concrete product is used.
2. Construction of load-bearing structures. They are filled with concrete after the installation of the formwork and reinforcing elements. The result is an all-cast concrete frame.
3. Installation of internal walls and partitions. If the elements are not part of the supporting structure, then they are made of foamed concrete or multilayer wall panels.
The monolithic frame house retains high reliability and resistance to seismic influences. But the possibility of redevelopment of premises is significantly simplified and the options for performing finishing works are expanded. This technology expands the list of architectural features of cottages. For example, arches, bay windows and panoramic glazing are often used.
A feature of monolithic brick houses is the possibility of filling the space between the load-bearing cast elements with brickwork.
Because of this, the technology of work execution is also changing a little:
1. The foundation and the formwork of the supporting elements are being filled in.
2. Builders manually carry out laying of brick walls.
3. Finishing works are carried out in a complex after the concrete has completely solidified and the brickwork has shrunk.
The construction of a monolithic brick house allows you to reduce the cost of renting special equipment. At the same time, the structure receives all the advantages of a brick house, such as increased thermal insulation or ease of redevelopment [5, p. 46].
The foundation for a monolithic house is a reinforced concrete slab with a thickness of 1 meter. It is cast directly at the construction site of the building. This allows you to connect it to the walls without seams. Piles can be pre-installed on weak soils to increase the reliability of the foundation.
The strength of monolithic structures is provided by reinforcement. This means that before pouring concrete into the formwork, a three-dimensional grid of steel rods is installed. They are twisted with wire or welded together. Reinforcement further prevents cracking of concrete structures, increases their resistance to tensile loads, improves the seismic stability of the house.
After pouring concrete into the formwork, it is additionally compacted to avoid the formation of air cavities. For this purpose, a deep vibrator is used. His mace is immersed in a concrete mixture. Under the influence of vibration, air bubbles rise to the surface and dissolve.
At the first stage of the construction of a monolithic house, the foundation is being arranged. A monolithic slab and a base for future load-bearing structures are being poured.
Further, the technology of building a monolithic house includes the following stages:
- assembly of the formwork;
- filling and compaction of concrete mortar;
- dismantling of the formwork, if removable shields were used;
- protection of the concrete surface.
The formwork is assembled manually or using special equipment.
Installation stages:
1. Plastic, steel or metal formwork is equipped with special fasteners or latches that fix the individual panels together. The wooden one is assembled with the help of screws and bars. It is important that the bars are located on the outside of the formwork.
2. If the foundation is being filled, then a roofing material or an oilcloth is laid on the bottom of the form-work, and sand or gravel is filled on top. This avoids the absorption of moisture and mortar by the soil, which could lead to a decrease in the performance characteristics of the monolith.
3. The film can also be fixed on vertical surfaces. But more often, technical oil - emulsifier is used. This improves the quality of the concrete surface after solidification of the monolith.
4. Before pouring concrete, check the evenness of the formwork in height and length. For this purpose, the building level is used.
The installation of the formwork for filling floors differs from the wall one:
1. Installation of metal tripods. These are racks that serve as a support.
2. Beams are laid out on the racks, which are fixed to the previously filled walls or load-bearing structures. Transverse beams are superimposed on the longitudinal beams, after which a certain grid is formed. The form-work panels, called the bottom, are laid on it.
3. The side panels of the formwork are fixed to the laid ones with the help of latches or self-tapping screws and bars. They are strictly aligned in height and checked for parallelism. The adjustment can be made using tripods.
4. The surface of the formwork is lined with a film. It provides the necessary tightness, which avoids the leakage of the concrete solution.
5. The formwork is filled with concrete at half its height. After it grabs a little, the reinforcement bars are inserted and the remaining part of the solution is poured.
Dismantling of the formwork is carried out on the 21st day after pouring the concrete mortar. This period may vary depending on environmental conditions (temperature, humidity). In 3 weeks, reinforced concrete dries to about 70% of its final strength [6, p. 48].
The dismantling of the formwork is carried out gradually. So, on the first day, they remove the shields from the corners. In these zones, the load-bearing structures have the least load. On the second day, the bars
and locks that fix the shields from the outside are dismantled. Only after that, the formwork elements themselves, into which the concrete was poured, are disassembled.
The formwork differs in several characteristics:
1. The material of manufacture. Aluminum, steel plates, plastic, wood, and expanded polystyrene are used to produce individual elements. The first forms were always made of wooden boards or plywood.
2. Practical purpose. The formwork can be wall (walls and vertical structures), horizontal (foundations, floors) and non-standard (columns, arches).
3. The shape of the elements. The formwork can be shield and tunnel. The first one is assembled from separate shields. This allows you to adjust the dimensions or shapes of individual monolithic structures directly on the object. The tunnel was initially adjusted in size according to the approved construction project.
4. The possibility of repeated use. It can be removable and non-removable. The first one after pouring and solidifying the concrete can be dismantled for reuse. The non-removable solidifies together with the concrete mortar and in the future is a structural element. Another subspecies of formwork is "floating". It is used when pouring a monolithic foundation immersed in the ground. The shields are attached to the walls of the pit. Along the perimeter, roofing or cardboard is fixed to them with screws.
References
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- S. 030-036.
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3. Savenkov A. I. Monolithic houses made of foam concrete / A. I. Savenkov, P. S. Gorbach, S. A. Shcherbin // Modern technologies and scientific and technical progress. - 2008. - T. 1. - S. 62.
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