Çok Katlı Çelik Yapılarında Döşeme Türü Kararı Etkenleri

Abstract

Yüksek yapıların 19uncu yüzyılın sonlarına doğru ortaya çıkmalarından bu yana inşalarında hafif olması, yapımının hızlı ve kolay olması, daha küçük enkesitli taşıyıcılara ihtiyaç duyması sonucu, çelik malzeme kullanılagelmiştir. Bu çalışma ile dünya üzerinde çok katlı yapının gelişimi ile inşasında kullanılan çelik malzeme hakkında bilgi verilmiştir ve çok katlı yapının taşıyıcı sisteminde önemli yer tutan döşeme sistemleri araştırılmıştır. Uygulanmakta olan döşeme sistemlerinin oluşturulma yöntemleri ve bu sistemlerin aralarındaki farklılıklar ortaya konmuştur. Tezin birinci bölümünde, ele alınan konunun amacı, kapsamı ve bu çalışmada kullanılan metot üzerinde kısaca durulmuştur. İkinci bölümde, çok katlı yapı tanımlaması yapılarak ortaya çıkış nedenleri, gelişmeleri, yapım sistemleri ve uygulanmış bazı çok katlı yapılar hakkında bilgiler verilmiştir. Bunun Türkiye'deki yansıması araştırılarak, örneklemeler yapılmıştır. Üçüncü bölümde, çelik malzemesi tanıtılarak, çeliğin yapı malzemesi olarak üretilmesi, çeşitleri, şekilleri ve yapı bileşeni olarak kullanılabilmesi için gereken birleştirme yöntemleri anlatılmıştır. Çelik malzemenin yapı çeliği olarak özellikleri incelenerek avantaj ve dezavantajları ortaya konmuştur. Yurdumuzda çelik üretimi ve sektörün sorunları, beklenti ve hedefleri hakkında bilgiler verilmiştir. Dördüncü bölümde çelik yapının nasıl planlanması gerektiği taşıyıcı sisteminin tasarım ilkeleri anlatılarak, taşıyıcı sistemi oluşturan, kolonların, kirişlerin, yatay ve düşey rijitleştirme elemanlarıyla, düşey sirkülasyon ve servislerin düzenlenme şekilleri anlatılmıştır. Çelik yapı bileşenlerinin imalat, depolama, taşıma ve montaj aşamaları ele alınmıştır. Çelik yapının korunma yöntemlerine değinilmiştir. Beşinci bölümde, yapı sistemi içinde döşemenin oluşturulması ve üstlendiği fonksiyonlar anlatılmıştır. Uygulanmakta olan döşeme sistemleri hakkında bilgiler verilerek, bu sistemlerin sağladığı avantajlar ile sistemi kısıtlayan etkenler anlatılmıştır. Çok katlı bir bina için hayati önem taşıyan ısıtma, havalandırma, aydınlatma ve yangın söndürme servislerinin nasıl planlanması gerektiği ve döşeme sistemi ile entegrasyonu incelenmiştir. Bütün bu servisleri, döşeme sistemi içinde gizleyen ve döşemeyi yangından koruma işlevi de üstlenen asma tavan sistemleri ve son olarakta döşeme üst bitişleri olan döşeme kaplamaları incelenmiştir. Sonuç bölümünde, yurdumuzda geniş kullanım alanı bulamasa da yakın zaman içinde betonarme sisteme bir alternatif olarak ortaya çıkması kaçınılmaz olan çelik iskelet sistemi için donanımlı olunması gerektiği vurgulanmıştır. Yurdumuzda uygulanan döşeme sistemlerinin standardlaştırılması, ülke şartlarına uygun sistem araştırılması ve ayrıca çelik yapımda prefabrikasyona yönelme gereği üzerinde durulmuştur. Çelik yapı malzemesi üzerinde ilginin yoğunlaştırılması ile hem inşaat sektörünün alternatif sistemlere yatkınlığının artacağı ve hem de ülke demir-çelik sektörünün gelişmesine katkı sağlanabileceği vurgulanmaya çalışılmıştır.

The nineteenth century was the age of great engineering feats and technical inventions. Iron architecture had brought with it a new quality of building. Iron had previously only been used as a construction material for small auxiliary components, tension rods and connections between ashlars in lintels and cornices. It emerged as an autonomous material with the construction of the first iron bridge. Construction with steel only became popular around 1830 due to its light weight and the narrow struts it made possible. As buildings grew taller, so did the advantages of steel construction. It burdened foundations with less weight, and made it possible to avoid the thick ground floor walls. One by one the preconditions for high-rise building were all met; the invention of a fireproof steel frame, the technology for sufficiently load-bearing foundations and, above all, the passenger elevator first introduced in New York. Important engineering and planning principles pertaining to high-rise buildings were resolved in these initial applications. These applications included aspects such as structural fire protection, regular grid spacing of interior columns and planning with respect to service functions of lighting, heating and plumbing. The inefficiency and the consequent massiveness of masonry walls as load bearing elements had been recognized and these masonry walls were gradually replaced by skeleton or cage buildings in which iron columns and beams provided the full support to all floors and the roof. For the most part, in the latter half of the nineteenth century, the components were cast iron for columns, brackets for supporting beams, and lintels, whilst wrought iron was typically used for beams. The tensile capacity of wrought iron was utilized in ties connecting the tops of columns and lateral beams rigidly connected to the columns by rivetting. This transformed the buildings into frames which could resist wind forces in addition to gravity forces. By the end of the nineteenth century steel had replaced forged iron beams and cast iron columns due to its economic advantage. In design terms, steel work meant longer spans to the interior and less massive envelope walls. Exterior construction went straight up in the line of the exterior columns giving a systematic rhythm and arrangement for the exterior fenestration. The clarity and distinction of this form of frame construction found its expression in the Chicago School of Architecture. Louis Sullivan structures the building in terms of three functions. The ground floor is thus for shops and for access to the upper floors. It is followed by a middle section containing any number of similar floors of offices. The top floor, which houses elements of the buildings utilities. His typical ideal multi-storey building therefore features a base, shaft and capital, as in a classical column. It had its meaning in the aspect of 'form follows function'. Ever taller buildings now sprang up at great speed. Highly-specialized teams of workers erected their steel scaffolding at dizzying heights, with Chicago, New York and also any other part of the world alternately outdoing each other. Therefore the structural clarity of earlier high rise buildings was completely destroyed, and it would take a long time before comparable achievements were once again reached. In recent years the development of steel-framed buildings with composite metal deck floors has tansformed the construction of multi-storey buildings. During this time, with the gowth of increasingly sophisticated requirements for building services, the very efficiency of the design has led to the steady decline of the cost of the structure as a proportion of the overall cost of the building, yet the choice of the structural system remains a key factor in the design of successful buildings. The principal reasons for the appeal of steel for multi-storey buildings are noted below; Steel frames are fast to erect. The construction is lightweight, particularly in comparison with traditional concrete construction. The elements of the framework are prefabricated and manufactured under controlled, factory conditions to established quality procedures. The accuracy implicit in the manufacturing process by which the elements are produced enables the designer to take a confident view of the geometric properties of the erected framework. The dryness of the form of construction results in less on-site activities, plant, materials and labour. The framework is not susceptible to drying-out movement or delays due to slow strength gain. Steel frames have potential for adaptability inherest in their construction. Later modification to a building can be achieved relatively easily by unbolting a connection: with traditional concrete construction such modifications would be expensive, and more extensive and disruptive. The use of steel makes possible the creation of large, column-free internal spaces which can be divided by partitions and, by eliminating the externel wall as a load- bearing element, allows the development of large window areas incorporated in prefabricated cladding systems. For the full potential of the advantages of steel-frame construction to be realized, the design of multi-storey buildings requires a considered and disciplined approach by the architects, engineers and contractors involved in the project. They must be aware of the constraints imposed on the design programme by the lead time between placing a contract for the supply of the steel frame and the erection of the first pieces on site. The programme should include such critical dates on information release as are necessary to ensure that material order and fabrication can progress smoothly. The building envelope, services and internal finishes must be co-ordinated by a firm dimensional discipline, which recognizes the modular nature of the components, to ensure maximum repetition and standardization. In principle, the design aims can be considered under three headings such as technical, architectural and financial. The designer must ensure that the framework, its elements and connections are strong enough to withstand the applied loads to which the framework will be subjected throughout its design life. The system chosen on this basis must be sufficiently robust to prevent the progressive collapse of the building or a significant part of it under accidental loading. As issues related to stength have become better understood and techniques for the strength design of frameworks have been formalized, designers have progressively used lighter and stronger materials. This has generated a greater need to consider serviceability, including dynamic floor response, as part of the development of the structural concept. For the vast majority of buildings the most effective structural steel frame is the one which is least obtrusive. In this way it imposes least constraint on internal planning, and produces maximum usable floor area, particularly for open plan offices. It also provides minimal obstruction to the routing of building services. This is an important consideration, particularly since building services are becoming more extensive and demanding on space and hence on the building framework. The design of a steel frame should aim to achieve minimum overall cost. This is a balance between the capital cost of the frame and the improved revenue from early occupation of the building through fast erection of the steel frame : a more expensive framework may be quicker to build and for certain uses would be more economic to a client in overall terms. Commercial office developments are a good example of this balance. Although at the beginning the high-rise buildings were essential, because of new construction systems and the expense of the building site, but later then the economic power led the big companies to have a taller building in order to advertise itself. In our country it had its echos in recent ten years. There have been built many of high-rise buildings especially in the big cities. But the construction system is still the conventional reinforced concrete system. Since steel is an expensive material in our country it has not been used in costruction of high-rise buildings yet. Despite the fact that the steel frame is for most of its functions become more cheap than the reinforced concrete. The Turkish constructors, architects and engineers are not familiar to steel construction. In order to build higher buildings, more resistable, quick, economic and functional we have to be keen on using the steel frame construction. The design of multi-storey frames must accommodate a range of functional, performance and economic requirements. Having decided on the structural grid which meets the needs of the building, the designer must choose an economic structural floor system to satisfy all the design constraints. The choice depends on the span of the floor, the service requirements and any of the height restrictions. There is clearly a very close interaction between the design of the service runs and the floor framing system and this can have a major influence on the building economics. In modern buildings the choice of a floor framing system is influenced by a number of factors. These include the following, not necessarily listed in any order of priority: a) Floor grids, taking account of the site and the user requirements. b) Floor-to-floor heights which may be restricted, for example by planning regulations or the need to relate to aesthetics or height limitations of adjacent buildings. c) Cladding costs, which for sophisticated systems such as window walls may be very expensive. The effect of envelope costs obliges designers to look critically at reduced floor-to-floor heights and this clearly has implications with regard to construction depth for structure and servicing. In this thesis it is aimed to determine the advantages and the disadvantages of the steel frame to the other systems and to explain the floor structures used in the high- rise steel framed buildings. The discussion of the design factors of floors is included to demonstrate the various options available to the structural designer and the process which should be followed in order to achieve a satisfactory solution. In the first chapter of the thesis, it is mentioned about what is aimed by writing this thesis and what are it's contents and which methods are used while forming the thesis up. In the second chapter, the reasons that made the high-rise buildings exist and the physical, the structural and the technological improvement of them all over the world is mentioned. The properties of the steel frame is described and while constracting a high-rise building why the steel frame is preferred and what advantages it obtains are defined. A list of high-rise buildings is given in which there is information about the designer, the costruction date, the height and the construction system of the buildings. In the end the conditions of the development of the high-rise buildings in Turkey is described and some examples are given. In the third chapter, the material of steel is decribed. Its manufacturing process is described briefly. What kinds of steel frame is produced is defined. The advantages and the disadvantages of the material of steel used as a construction material is described. Finally the Turkish steel manufacturers problems, expectations and their targets are determined. In the fourth chapter, the way of planning a steel frame is defined. Design criterias of the steel structural system and the the components of the system such as the columns, the beams, the vertical and horisontal rigidity elements are defined. Vertical circulation and the services within the structural system is described. The process of steel framing and production, stocking, transporting and constructing of it's components is described. Fire resistance and corrosion prevention of the steel framed building is described. In the fifth chapter, the floor systems which have an important role in the building structure system is described. How the system is formed and which of the functions it undertakes is defined. The information about the common floor systems which are in application are described briefly. In which conditions which floor systems should be used and what are the advantages and the disadvantages of these systems are defined. The importance of forming the floor system, cause it effected the design criterias of the structural system of a building, is defined. The modern high-rise buildings must have services which are very essential for their safety, comfort and functionality. These services are heating, air ventilation, lighting, fire protection and etc. In this chapter, forming of these services and integration of them with the structural floor system is also described. Hanged ceilings which have the function to hide these services in the floor cavity and protect the floor from fire are described. And finally, floor covering systems are described, so that the floor should be handled as a system with its upper and lower functions. In the conclusion chapter, it is determined that altough it could not have recently the opportinity of being used commonly as a system of construction in high-rise building, the steel frame has to be in the consideration of the constructors. The steel frame is a serious alternative to the well known conventional concrete system. It is also determined that the standardization for the floor systems which are used in our country should be made and new floor systems should be searched that will fit the conditions of our country. The importance of prefabrication in the steel construction system is described. By using the steel to form a structural system especially in high-rise buildings, the constructors will have opportinities of using new alternative systems in building construction. In order to get familiar to the contemporary construction systems we have to educate our technical person. The steel construction system must be clearly described, the advantages of using it must be determined so that the prejudice should be prevented. In the suffix part there are photographs of some applications of the steel structure and the floor systems.