Modular buildings in modern construction
Abstract
The article considers temporary methods of using modular units in construction. The advanced world experience in the construction of modular buildings is analyzed. It is emphasized that modular construction has the potential to shorten project design and engineering time, reduce costs and improve construction productivity. The installation of modular buildings is cost-efficient, safe and eco-friendly. Modern modular systems are based on using not only large elements such as «block rooms» but various small 3D building elements. The analysis result of Russian developments in the construction of modular buildings proves that Russia has great experience in the development of 3D reinforced concrete modules. As the research results the article shows promise for developing modern modular construction systems in order to provide the population with affordable, comfortable and eco-friendly housing. The paper describes the prospects and relevance of introducing modular prefabricated units not only into low-rise but into multi-storey and high-rise construction as well.
Keywords:
Modular construction; Prefabricated blocks; 3D block construction;
Modular high-rise buildings.
1. Introduction
In a number of studies and reports of «Habitat's
UN,» it is emphasized that rapid urbanization is accompanied by aggravated housing problems. The cities are growing disproportionately to the rates of economic development thus
increasing the gap between the poor and the rich. The megacities with over 10 million population are the symbols
of our time, but, unfortunately, they mostly do not mean such concepts as comfortable living environments,
The development of mass
affordable housing
construction is relevant for many
countries. Economically it can be justified only as the result of applying modern industrial construction
methods
that are based on standardization, unification
and typification. Modern materials and construction
systems are introduced under the condition of
extensive use of energy-saving technologies
[3-11]. The efforts of specialists are aimed at searching the ways of
reducing construction costs. It should be noted that nowadays the construction from offsite fabricated modules, in other words, modular construction
is one of the most promising and high-tech directions of architectural and
construction development in the world.
Modular technologies are
widely
used
in low-rise buildings of
different
functional purposes: office
and
household, warehouses, sanitary and special purpose premises, etc. However, in recent years, they have been
introduced
in multi-storey and even in high-rise construction. Modular construction combines various technologies
based on rapid construction principles. The concept of «modular building» should be focused on. In modern understanding,
talking about the modular components
of
the system, two main directions in the construction
of modular buildings can be distinguished: the use of separate elements of a frame system (beams, columns, floorings,
wall
panels, etc.) that are produced offsite and assembled onsite; the use of 3D elements (block containers) including
necessary internal engineering facilities, interior and exterior finishing and built-in furniture and equipment. It is
proposed to consider these directions in detail on the examples of advanced world experience in modular construction.
2. Prefabricated building construction systems
Prefabrication, pre-assembly, modularization, system building and industrialized buildings are the terms which
are used in the correlation and individually
for describing the advanced technologies in the rapid construction
of buildings when structural components
are
produced at a plant and the construction site is used only for assembling. In this section special attention is paid to systems based on separate structural elements produced at a plant.
The first example is the unique technology developed in China by the BROAD Group founded in 1988. Its production complex is based in Changsha. In 2008 its subsidiary company Broad Sustainable Building (BSB) was established with the production (BSB Central Factory) in Xiangyin, Hunan. 7 principles of sustainable development are in BSB construction technology: 1 – it is the only enterprise in the world where 90 % of modular system components are offsite prefabricated elements (production wastes – 1 %); 2- energy consumption efficiency is 5 times higher than in traditional buildings; 3 – unique microclimate inside buildings with specially purified air; 4- seismic resistance (withstands the earthquake of magnitude 9); 5 – land saving (focuses on high-rise construction); 6– the saving of materials (metal structures from recycled steel); 7- durability.
The structural system is based on the type-design practice of all elements: steel columns, beams (crossbeam), floorings and curtain wall panels. The most interesting module is the floor section of approximately
12.5m ɯ 4.1m (see Fig. 1a). They are produced
and equipped with necessary engineering facilities and finishing at a plant: electrical cables, concealed air outlet ports of central air conditioning and ventilation systems, heat and sound
insulation, finishing details, etc. The standard
height is 3.0 m. The produced modules are delivered to a construction site
and assembled by bolted and welded
joints. Typification of elements, high-quality offsite fabrication and perfect logistics (production, storage, delivery, assembly) allow for reaching amazing construction rates [12, 13].
The corporation has constructed over 30 buildings since its establishment. The following buildings are among them: a 15-storey hotel built in 6 days; a 30-storey hotel «T30 Hotel» (2012, 99.9 m) in Changsha (China) built-in 15 days. Not stopping on the achieved results, BROAD Group has started an ambitious project: the construction of a building «Sky City» (838m) using their modular system (see Fig. 1b). This skyscraper is presented as a real «vertical city» of 202 floors. 83% of the building area must be used as residential apartments for about 17000 habitats. Besides, offices, a hotel, 5 schools, a hospital, stores, restaurants, 17 helipads, 6 basketball courts, 10 tennis courts and other things are provided. But the height of the skyscraper is not the most important component of the construction revolution. The unique fact is that it is planned to be built in an enormously short period of 90 days.
One more example of introducing prefabricated structures in the construction of affordable public housing is in Hong Kong (see Fig. 2b). Prefabricated large-size elements are used in the construction of 40-storey residential buildings. Thus, mechanization, quality and construction safety increase; construction wastes are minimized; the level
of noise and air pollution at construction sites decrease. Prefabricated elements of different complexity are produced: modular facade panels, semi-fabricated plates, and three-dimensional fabricated elements (kitchen units, bathrooms, garbage chutes, elevator shafts etc.). Standard zones are designed for engineering systems (gas supply, water supply and drainage) that are laid outside the house along the facade [14-17]. To optimize the number of typical structural elements Modular Flat Design has been applied in the latest decade. There have been developed 4 types of planning concepts for apartments. The modular approach provides the design development for residential houses under particular urban planning conditions.
3. Modular buildings of 3D blocks
3D modular house construction is a type of prefabricated construction based on applying 3D blocks produced offsite in advance. Their use has a number of advantages: assembling speed; high-quality control at a plant; work safety as the time of high-altitude works shortens; testing and rapid introduction of new technologies at the plant; a decrease of noise level and the amount of construction waste at a construction site that has a good impact on the environment, etc. The material for the constructive framework is reinforced concrete or a metal frame.
This type of construction has a long history in Russia. In Soviet times 3D block house construction was successfully introduced. It was one of the most promising methods providing a high construction rate for residential buildings. In 1974 the production of reinforced concrete 3D block structures was launched in the Krasnodar region for the construction of residential houses of BKR-2 type developed by the Institute of Complex Design of Residential and Public Buildings in Moscow. The plant «OBD» operates and develops up to nowadays. The production line is designed to produce over 50 blocks per day. The size of the base member is 3.4m x 2.5m x 6.0 m. The area of a standard «block room» is 19.6m². Depending on the functional purposes there can be installed additional partitions, ventilation units, stairways, etc. Since 2005 almost all the residential buildings built from the blocks that are produced at the plant have 16 floors. The construction of a three-section residential house takes one month [18]. Although the achievements of this plant in the field of 3D block production are based on long-term experience in
construction, design and operation, it should be noted that visually the final product has changed little. The facades are unvaried and do not correspond to the current trends in architecture. One more negative point about this technology is that 3D blocks require considerable costs for interior finishing and equipment installation after assembly.
There are some other examples illustrating the development of Russian 3D block house construction. In the industrial park «Maslovsky» in the Voronezh region a factory for the production of 3D blocks «VYBOR-OBD» was founded in May 2015. The technology makes it possible to erect 17-storey buildings. It takes only 4 days to assemble one floor of a 4-porch residential house [19]. After assembling the building requires external coating. For this purpose, a ventilated facade with metallic panels made from galvanized steel with polymer coating is used. It gives a building a modern look (see Fig. 3). As in the example given above the interior finishing and the equipment installation are made after a building’s erection.
Er. SP. ASWINPALANIAPPAN., M.E., (Strut/.,)., (Ph.D.,)
Structural Engineer
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