Prefabricated modular structures of industrial buildings made of folding sections as up-to-date construction method

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FESTU

Prefabricated modular structures of industrial buildings made of folding sections as up-to-date construction method

Angarskiy E.V., Piotrovich A.A

Khabarovsk, Russia

Abstract

The article gives a brief summary about a brand new technology for Russia of offsite folding construction, the history of its origin and development. It describes the importance of developing that method of building structure construction from the standpoint of environmental safety as well as economic efficiency of application. The article presents the main differences of such prefabricated structures as compared to the conventional elementwise erection of buildings and structures at construction site. Different approaches to construction of facilities in low temperatures, within tight deadline and on unstable soil base have been analyzed.

Keywords: modular construction, prefabricated construction unit, modular building.

Introduction

(Historical background; Russian and international practice). Questions of decreasing the time of construction and improving technical and economic indicators in the areas of adverse natural conditions are not revolutionary new.

A modular method of construction is widely used in the development of fields located in the remote areas away from big cities; for construction in new regions; and in case of emergency. Modular construction has a great potential in the sphere of construction of buildings and structures in the areas of natural disasters, as well as in urban areas exposed to man-made problems and conflicts [2].

The first attempts to create modular buildings were undertaken in the first half of the XX century. However, the main purpose of the first modular structures was to create a type design practice and establish standards for construction, without emphasize on the opportunity to reuse these assemblies. The peak for prefabricated modular construction was in the second half of the last century [3,5].

Nowadays, among the existing prefabricated methods of construction the following types and related problems can be distinguished:

modular buildings made of container units. A range of application is limited because of the small size of a typical standard module. In case of increasing the width of the room beyond the dimensions of the container, additional columns are required to be installed. Such method of construction is applied to accommodation camps and office buildings;

metal tent constructions. The main drawbacks of that method include shipment of disassembled and elementwise erection at the construction site [4];

ffameless modular buildings. The limited high of structure and implied installation at construction site are the weak points of that method. It is applicable for construction of small auxiliary buildings and offices;

pneumo-framed modules. Necessity for continuous use of hot air blowers, air pumps and low resistance to damage significantly limit the applicable scope of such structures in regions with high energy cost.

Quite recently, an innovative modular construction method based on pre-fabri- cated folding sections has appeared. This method is devoid of the drawbacks mentioned above and has a number of advantages in comparison with traditional construction methods. folding temperature soil building

Basic elements of pre-fabricated modular folding buildings are:

foundation (prefabricated reinforced concrete or monolithic concrete slab);

frame of the building, which represents an assembly of all rolled steel elements connected by movable joints and filler structure made of sandwich panels (including a roof part). All the constituent elements are combined into a single compact unit, prefabricated at the factory and made ready for transportation, which later on is transformed into a three-dimensional section of the building at the construction site;

elements enhancing structural rigidity: the locking beams and cross-tension cables, embedded anchor bolts, doors and gates, power supply and lighting elements.

Among the new principles of such type of modular building construction a maximum of prefabricated state of the main elements of the building should be distinguished. The basic idea of the design and construction of this method is the "Transformer" principle. After shipment of "Transformer" to the site, a construction company needs only to install a ready-made "semi-finished" structure on the foundation and complete final assembly of the integrated units. During the construction of a typical warehouse only a minimum set of equipment is required - one mobile crane and one manlift. The number of personnel involved in modular construction is much less than that required for elementwise construction.

Unfortunately, in our national practice almost all elements for that type of construction are imported. The leading countries in the field of prefabricated construction are the USA, China and a number of European countries (Hungary, Germany). A vast majority of Russian factories manufacturing products for modular building are located in the western part of the country.

Methods, materials and construction process description. A typical process of erection of a prefabricated folding building includes the following steps (fig. 1):

Preparing foundation pad;

Installing foundation (installing water-tight layer and reinforcement bars). PVC liner is installed to prevent potential spills of hazardous substances. Installing reinforcement bars between perimeter foundation pavers gives additional strength to foundation

Relocating modules to the construction site

Preparing a folding section for installation. Joining two halves of a section by bolted connections. Removing shipping fasteners;

Installing a folding structure with use of crane and a spreader bar. Hooking a spreader bar to the crane boom. Lifting a section with use of a spreader hooked to lifting eyes till a complete opening of the structure forced by gravity. Fixing the structure in the design position;

Installing locking bolts and anchors;

Installing end walls. Tensioning transverse steel cables;

Installing insulation in panel joint areas. Installing trims;

Installing power supply and lighting systems;

Installing a stand-alone external heating station (optional);

Installing fire alarm systems and outfitting of the building (optional);

Installing fire water pipelines and technical water pipelines (optional);

Installing water treatment systems and sewage treatment systems;

Testing and commissioning.

Fig. 1. Milestones of modular building construction (a Warehouse is taken as an example): a) preparation of a section for installation, b) installation of a section, c) folding section installation process, d) installation of a section with an opening for gates, e) installation of the last section of warehouse, f) end wall installation, g) completedfolding facilities

Results (Economic and environmental indicators)

The main advantages of prefabricated folding construction can be identified as:

All seasons construction. Construction of the folding buildings does not include "wet works", and the first mounted section is in itself a shelter from adverse weather conditions during preparation of further scheduled works. Installation of prefabricated modules can be carried out at any time of the year under almost any conditions.

Mobility. It gives a possibility to change location of a structure. A folding building can be disassembled within a short period of time, transformed into its original ready to be transported state with use of a spreader bar, and can be reinstalled at a new location. To dismantle and disassemble a folding building a minimum set of equipment and manpower is enough (1 crane, 1 manlift and 10 workers). Folding buildings are lightweight and require minimum costs for transportation and foundation installation. Mobility of folding facilities is comparable with the buildings made of modular containers.

Seismic resistance. Prior to manufacturing at a factory, all folding structures are estimated for static and dynamic loads, as well as for seismic load. In general, a folding system allows to resist high seismic forces. According to the estimations, a modular folding building is able to withstand an earthquake up to 9 by the Richter scale [1].

Simplification of the design and commissioning. As a rule, modular buildings are built according to typical designs. Therefore, there are no issues with design approval by regulatory institutes.

Environmentally friendly type of construction. Folding buildings are manufactured in compliance with all environmental safety requirements. Firstly, it relates to environmental compatibility of materials themselves. Secondly, installation of modular buildings practically does not create hazards to the environment, unlike elementwise construction method, around which all the flora and fauna become extinct at the area for severed years caused by construction equipment and aggressive substances [7]. General environmental indicators are depicted in the table 2 are: a) Emission of pollutants; b) Waste accumulation; c) Flora, fauna, soil and ground disturbance; d) Use of water resources.

Table 1. Environmental impact cawed by a typical warehouse 78x24 m construction by different methods

- A short construction period. High speed of erection is due to the fact that modules are assembled at a factory and are delivered to site in a state completely ready for installation (fig. 2). Therefore, the process of a typical warehouse installation includes joining of modules and insulating of joints, and lasts no longer than a few months. So, less than a year is enough to build a whole industrial complex with complete infrastructure.

Fig. 2. Construction schedules comparison

Table 2 shows general indicators of a typical warehouse construction by two different methods.

Table 2. Indicators of a typical warehouse 78x24 m construction by different methods

The main disadvantages of prefabricated folding construction include simplicity and uniformity of architectural solutions. If a structure is assembled from ready-made blocks, any originality can affect the usability and functionality of buildings [6]. However, for the industrial objects that issue is not a problem at all.

Conclusion

For temporary type of buildings, prefabricated folding construction method is perfect and largely valuable. It does not require massive construction of foundations and heavy elements of a building. Prefabricated structures and bolting connections allow multiple relocation of a building without any additional consumption of construction materials within short time. Among ways to improve modular construction technology, separate manufacturing of independent elements depending on the availability of local resources can be highlighted.

In Russia folding construction represents great potential for solving contemporary problems that inevitably arise in the context of increasing global integration and competitiveness of developing countries. There is no doubt about benefits of implementing such design and technological solutions for realization of current programs on the territories of priority development in the Far East of Russia. Development of typical projects of such buildings for undeveloped grounds, implementation of social and cultural programs for the low budget municipalities is a very prospective direction. The following types of folding facilities can be used: a) administrative buildings; b) meal stations; c) hospitals; d) schools. Moreover, folding buildings can be used as sport and social facilities as well as in the aftermath of disasters and accidents, when the speed of erection of temporary places for accommodation and service plays a crucial role.

Bibliography

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2. Asaul A.N., Kazakov Y.N., Bikov V.L., Knyazev I.P., Erofeev P. Y. Theory and practice of prefabricated buildings application - SPb.: Gumanistika, 2004. - 472 p.

3. Belokonev E.N., Abuhanov A.Z., Chistyakov A.A. Basics of architecture of buildings and structures: Study guide. - Rostov-on-Don: Fenix, 2005. - 256 p.

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