THE USE OF MONOLITHIC REINFORCED CONCRETE IN CONSTRUCTION OF MULTI-STOREY BUILDINGS AND STRUCTURES

ПРИМЕНЕНИЕ МОНОЛИТНОГО ЖЕЛЕЗОБЕТОНА В СТРОИТЕЛЬСТВЕ МНОГОЭТАЖНЫХ ЗДАНИЙ И СООРУЖЕНИЙ

Рахматуллина Эльвина Ринатовна

студент, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

Гончаров Андрей Иванович

студент, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва,

Юдина Ирина Ивановна

преподаватель, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

ABSTRACT

This article deals with the relevance of the use of monolithic reinforced concrete in the construction of high–rise buildings with any architectural and planning solutions, it determinates the advantages and disadvantages of using monolithic reinforced concrete in the construction of residential and office buildings.

АННОТАЦИЯ

В данной статье рассматривается вопрос актуальности применения монолитного железобетона в строительстве многоэтажных зданий с любыми архитектурно - планировочными решениями, определяются преимущества и недостатки монолитного железобетона при строительстве жилых и офисных зданий.

Keywords: construction, high–rise buildings, monolithic reinforced concrete, architectural and planning solutions.

Ключевые слова: строительство, многоэтажные здания, монолитный железобетон, архитектурно – планировочные решения.

Currently, the construction of high–rise buildings and structures is mainly gaining popularity in the world, thanks to which it becomes possible to solve important problems - to provide housing or offices to as many people as possible, thereby meeting the needs of people. Monolithic reinforced concrete frames are considered to be more effective frameworks, specifically for high-rise buildings. With the help of this technique, it is possible to erect high-rise structures that amaze with their efficiency and safety.

The achieved level of monolithic concrete technology undoubtedly places high demands on the qualifications and experience of specialists involved in design and construction.

Monolithic reinforced concrete is one of the most durable and practical building materials. Buildings made of monolithic reinforced concrete are of the "comfort" type and higher. It should be emphasized that dwellings can be of any size and configuration, the apartments in new buildings of monolithic or monolithic-frame class can have a free layout and they can be very spacious. The distinctive features of the monolithic reinforced concrete building are distinguished by non-standard design solutions and unique architecture.

Monolithic reinforced concrete is a composite building material based on steel reinforcement and concrete itself. The monolithic mold is cast directly on the construction site. The construction of monolithic reinforced concrete buildings is accompanied by the following technological processes:

• connection of the frame with metal rods;

• creation of a formwork – a structure made of wood around a structure made of rebar;

• filling of the constructed tank with concrete mortar;

• monitoring the solidification process and continuation of the construction of the monolith in the same way; after solidification of the reinforced concrete structure, it is required to dismantle the formwork.

After casting the building structure, builders eventually get a solid shape in the form of a high–rise building. The floors of the house and the reinforced concrete foundation are rigidly interconnected. There are no joints and seams between them – a reinforced concrete monolith is obtained. Thanks to this technology, a high-rise building can withstand magnitude eight earthquake.

The technology of monolithic construction was developed about a hundred years ago, if not more, but in Russia it was actively used only 30 years ago and became an alternative to panel reinforced concrete buildings. During that period of time, the USSR needed rapid construction and resettlement of citizens, so panel houses were the best option. Individual structural elements were cast at a special factory and then they were assembled as a constructor on a construction site. Therefore, such houses were built quickly, in 6-9 months. However, this technology caused a number of problems at that time.

Firstly, additional factories and equipment were required for the manufacture of reinforced concrete panels. Secondly, the panels at the factory were cast in identical shape, that is why all the buildings were similar to each other, and the conversion to a different style required significant costs. And these were the main drawbacks.

When all these problems became obvious, the builders remembered the structures made of monolithic reinforced concrete which solved most of the actual problems of panel houses and met the current requirements of future residents.

So, in a short time in Russia, it was possible to organize mass production of a new generation of concrete with increased strength, corrosion resistance, low water permeability and frost resistance. In the mid-90s in Moscow, the volume of monolithic construction was about 60%, prefabricated - 40%, and currently 70% and 30% of buildings and structures constructed of monolithic reinforced concrete account for 70% and 30%, respectively. It should be noted that in the period from 2000 to2005, only at the enterprises of Closed Joint Stock Company “Mospromstroy”, more than 750 thousand meters of reinforced concrete structures were erected, of which:

• 50 thousand square meters - made of high-strength concrete of classes B50-B60 and above;

• 250 thousand square meters - made of high-density concrete with high corrosion resistance;

• 50 thousand square meters - made of concrete of classes B30, B45.

More than 965 thousand cubic meters were built at the facilities of Public Corporation “Concern Monarch” in the period from 2005 to 2009. At the same time, several technological tasks were solved: ensuring low exothermic heat, cohesion - not stratification of highly mobile concrete mixtures, ensuring high initial strength of concrete without heat treatment and a number of other tasks.

This technology is not perfect; it has quite a lot of disadvantages, but first let's list the advantages:

1. From the name of this technology - it is clear that the structure turns out to be a single, monolithic, without seams, which are present in panel and brick houses. And this is one of the main advantages of this design. Since there are no seams, the building turns out to be very strong. Also, thanks to this, the load is distributed evenly on all load-bearing structures and therefore a lightweight foundation can be used. The absence of seams also has a positive effect on noise insulation and thermal insulation.

But there is also a downside. If the sounds of music, voices or TV are really better suppressed by a monolithic structure, then mechanical sounds, such as drilling a wall or various blows, on the contrary, spread even more. This problem is solved with the help of additional noise insulation of the entire apartment.

2. Next, we should describe the construction process of monolithic buildings. Almost all work is carried out on the construction site. To get a good result, employees must be prepared in advance and they should have professional experience. With proper construction, such a building is considered the most durable. The service life of such a structure is about 100-150 years. Also, due to the solidity of the structure, such buildings can be erected on unstable soils, having previously installed piles under the foundation. The most striking example in the use of such a foundation is the Burj Khalifa skyscraper, located on weak soils with the help of reinforced concrete piles. Monolithic reinforced concrete is also distinguished itself in the construction of high-rise buildings. It is much cheaper than a steel frame, while it has even greater strength. No one disputes that a steel frame is lighter, so most often a combination of a frame and monolithic reinforced concrete is used. Burj Khalifa, a building about 800 meters high, is made of monolithic reinforced concrete.

3. Another undoubted plus is that with the help of monolithic concrete, you can implement various ideas and make architecture diverse. This creates a variety of buildings and makes neighborhoods and cities more aesthetically pleasing. Concrete is a very durable material, so at the design stage it is important to consider the location of all openings for the sewerage system, heating system and for other systems.

4. Another undoubted advantage of a monolithic building is the simplicity of redevelopment. If in panel buildings all the interior walls are in fact load-bearing, then in monolithic buildings there are significantly fewer load-bearing walls, the walls between the rooms can be placed exactly, as the owner of the apartment wants. This gives huge opportunities for redevelopment, because it becomes real to equip the apartment to the maximum according to the personal requirements. The only exception, perhaps, is that the bathroom or shower should be in approximately the same place, called the "wet zone".

Let's list the disadvantages of monolithic buildings and how these technologies cope with them:

1. Probably their biggest disadvantage is the difficulty of working with concrete.

It starts with the weather conditions, because the construction of the building has been going on for more than a year, and, therefore, continuous work is required both the heat and the cold. The optimal temperature for pouring concrete is 15-25 degrees. When the temperature deviates from these ranges, the strength of concrete is noticeably reduced. However, this problem was practically solved by adding frost-resistant additives to concrete at subzero temperatures and using the technology of adding ice to concrete at excessively high temperatures. This creates difficulties in the manufacture of a monolithic structure, but they are not so significant.

2. Another feature that can hardly be called a disadvantage, but which cannot be overlooked, is working with concrete on a construction site. Where will concrete be poured during the construction of floors?Formwork is used for concrete molding. Builders are improving the types of formworks used for greater practicality. There are formworks made of iron, aluminum and there is also a sliding formwork. When erecting high-rise buildings made of monolithic reinforced concrete, the most effective arrangement of structural elements is considered to be one that allows the formwork to be used repeatedly without additional costs. The use of formwork systems in monolithic construction makes it possible to erect buildings of any number of floors and configuration. One of the most popular types of formwork systems on the market is demountable formwork. Once the formwork is assembled, the reinforcement is made and concrete is poured. If a pit is small, it is necessary to drive the car with concrete and pour it. Technologies that allow people to conveniently pour concrete were invented. For example, there is a special machine with a hose and a pump for feeding concrete. Concrete is poured into such a machine, and it feeds concrete up with the help of a pump and allows you to build buildings of low height and to pour a large area of foundation. However, if the building is too high, such a pump is useless, and the concrete is raised to the required height with the help of tower cranes and special containers where concrete is poured. Once the concrete is finally poured, the work does not end there. In order for the building to be strong, it is necessary that the concrete evenly fills the entire space. To do this it is necessary to use a deep vibrator which helps to pour concrete correctly.

Conclusions:

1. Monolithic reinforced concrete is used everywhere in modern construction, which is explained by its excellent characteristics such as reliability, strength, durability.
2. Due to their technological features, monolithic buildings are much more resistant to external factors.
3. Provided that only high-quality materials are used correctly in the work and all stages in compliance with the technology are followed, monolithic reinforced concrete allows you to create a variety of structures and to demonstrate excellent properties.
4. If the design life of panel buildings is 50 years, then the design life of building built with monolithic technology is at least 200 years.
5. As for the cost, we can say it is quite comparable to the cost of panel buildings. Some difference in price (if there is one) is explained, as a rule, by the external properties of the facade. The more complex the idea of the designer and architect, the higher the price. The cost of construction is affected by the correct organization of work on the construction site and the compliance with the funding schedule.

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