DEVELOPMENT AND IMPORTANCE OF PREFABRICATED BUILDINGS IN TURKEY

With the ever-developing technology, industrialization in Turkey and the world, the prefabricated sector is also developing. The speed element is one of the main reasons for choosing the prefabricated sector. In case of urgent need due to reasons such as natural disasters, refugee increase, construction site mobilization buildings, prefabricated buildings quickly meet the need for shelter. However, the sector is growing with the increase in demand and prefabrication technology is developing day by day.

The low total cost of the project, its rapid completion, ensuring the desired quality and strength in the building elements, reducing material waste, increasing modulation and standardization opportunities, and significantly reducing the number of work accidents that may occur on the construction site have accelerated the sectoral growth.

Prefabricated construction has been used in the world for a long time, and it started to be implemented in Turkey in the early 1965s.

In 1965, portable camping houses were put on sale for the first time in Turkey. Houses made of poplar wood in two different sizes were sold for 3 thousand 500 to 2 thousand 750 liras.

Although the prefabrication sector in our country is a sector open to development, it has had an unfair image in the market in the past due to problems such as the dominance of the traditional reinforced concrete system and underhand manufacturers. Due to this situation, the pace of development has not been in a certain order. In addition, the lack of adequate promotion has been an important factor in the underdevelopment of prefabricated buildings in our country compared to European countries.

In Europe:

• The share of prefabrication in the construction industry is 30-50%
• Prefabricated superstructure projects include all types of structures (low, high, residential, office, industrial, sports) etc.
• Prefabricated buildings built in earthquake zones are increasing.
• There is a lot of R&D regarding earthquake-resistant prefabricated building design.
• The regulation for prefabricated building design is quite detailed.
• There is also a comprehensive regulation for the earthquake-resistant design of prefabricated buildings.
• Multi-storey prefabricated buildings are quite common.
• Prefabrication subject to a certain quality control process in superstructure construction: ~95-100%

In Turkey:

• The share of prefabrication in the construction industry is 2-3%
• Superstructure projects are typically low-rise / wide-span hangar type industrial buildings
• Limited R&D regarding earthquake-resistant prefabricated building design
• The scope of the regulation regarding prefabricated building design is insufficient
• The number of multi-storey prefabricated buildings is low
• Prefabrication subject to a certain quality control process in superstructure construction: 53%

However, in recent years, the prefabricated sector has been shown as one of the rapidly growing sectors both globally and nationally.

The prefabricated sector, which has increased its growth rate with the rapid development of the construction sector, includes concepts such as quality, speed, economy and continuity thanks to prefabrication technology. The sector, which has started to have a say in the Turkish economy, is increasing its importance in the Turkish construction sector day by day with the standardization in the production and application phases.

The number of prefabricated and steel mass housing buildings designed recently has increased because they can be built quickly and practically. The widespread use of steel buildings, especially after the 17 August earthquake, also had a positive impact on the prefabricated sector. Industry officials claim that the reason behind the increased interest in prefabrication since 10 years ago is awareness about earthquake-resistant buildings. The increase in the number of prefabricated companies after the earthquakes is also considered an indicator of growth.

The leading companies of the sector think that the expansion of the prefabricated sector should not only be due to the fact of earthquakes, but also that joint studies that can contribute positively to the growth process should be carried out and the awareness capacity should be increased both globally and nationally. In addition, prefabricated industry authorities argue that the importance of energy efficiency and improved building materials will gradually increase due to legal practices and sanctions to increase construction quality.

The light steel construction sector, which started to develop especially after the 17 August earthquake, continues to develop rapidly. It is predicted that the sector, which has an increasing market share in the construction sector, will continue to grow, especially with urban transformation projects. 90 percent of light steel structures are produced in production facilities. Only the assembly part is created on site. A four-storey building is completed in approximately 30 days. This speed is not found in any building system. Light steel structures attract attention as the right solution for urban transformation projects. These structures are built in a very short time and stand out with their earthquake resistance and high heat and sound insulation.

The fact that the light steel structure system is economically more advantageous than reinforced concrete structures because it is built faster than reinforced concrete structures and provides heat and energy savings has become more widely known in recent years. In addition, the structures built with the light steel construction system have high insulation properties as well as earthquake resistance.

With the developing technology, the lifespan of prefabricated buildings extends from 50 to 80 years, depending on the type of construction and materials used. The development of prefabricated structures is improving day by day with the build-apply method. While these structures initially provided a disadvantage in terms of sound and heat insulation, this disadvantage has been turned into an advantage with alternative insulation applications. In fact, prefabricated building systems can now be applied even for structures that require a high level of thermal insulation, such as cold storages. Prefabricated buildings are frequently preferred in construction sites both at home and abroad in order to accommodate workers and meet their social needs due to their quick installation and, most importantly, low cost. The prefabrication system has the feature of being revised in line with supply and demand, depending on the conditions of use and the geographical situation of the place to be used, without going through the fabrication process. This has been one of its biggest advantages. The light steel prefabricated structure can generally be installed on lean concrete in order to equalize the ground level in the area where it will be installed, without the need for any foundation structure. If heavy steel materials such as hangars are used, it is also possible to use lean concrete without using a chassis.

A big plus is that it does not cause any harm to the environment, both during the fabrication process and the assembly phase. Steel prefabricated structure is mostly produced from sandwich panel system on a C-section carcass skeleton. In case of using modular light steel structure, it is also easy to transport and can be cleaned conveniently. Among modular buildings, the most commonly used form in our country is the container. After the parts are produced, they are assembled in the factory and all kinds of mechanical and electrical installations are added, and they can be loaded onto trucks according to the container dimensions, unloaded to the area where they will be used with the help of a crane, and can be used immediately. In our country, the shelter needs of people living in the region and becoming homeless after the Kahramanmaras earthquake were met in this way.

In order to increase the share of the Prefabrication Sector in Turkey, the impression that Prefabrication is a system suitable only for industrial buildings should be eliminated. The advantages of prefabrication should be highlighted, especially in the project design of multi-storey buildings. The awareness of civil engineers should be increased through training, especially regarding connection points, in the design of earthquake-resistant multi-storey buildings. For the efficiency of these trainings, a national comprehensive prefabricated building regulation should come into force. One of the most important reasons why prefabricated buildings are not developed in Turkey is the lack of R&D studies on earthquake-resistant prefabricated building design. For this purpose, efforts should be made to ensure that the sector benefits more from programs such as AFAD - National Earthquake Research Programme.

75% of the construction industry in Turkey is residential type buildings, where the share of prefabricated housing in the buildings is 1-2%. It is understood from here that increasing the share of prefabricated buildings in multi-storey residential buildings will play an important role in the development of the prefabricated sector. The use of new technologies in prefabrication should be supported in order to develop the advantages that prefabricated buildings offer in multi-storey buildings in earthquake zones.