Bir uçak hangarı inşaası için ekonomik sistem araştırılması

Bulduk, Ali Tahir
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Fen Bilimleri Enstitüsü
Bu çalışmada, bazı tipte ki uçakları barındırabilmek için, 50m x 50 m. alanında ve 16 m. yüksekliğinde bir yapının oluşturulması için farklı statik özelliklere sahip iki değişik sistem düşünülmüştür. Bu sistemler hesaplanıp boyutlandırılmış ve bazı çizimleri verildikten sonra ekonomik karşılaştırmaları yapılmıştır. Tez dört bölümden meydana gelmiştir. Birinci bölümde, çalışmanın amacı ve ele alınacak farklı yapı sistemleri hakkında genel anlamda bilgi verilmesi ile kullanılacak hesap yöntemleri belirtilmiştir. İkinci bölümde, çatısı kafes sistemle inşa edilen sistem incelenmiştir. Uygulamada çok rastlanan iki tipte makas sistemin cremona yöntemiyle çubuk kuvvetleri bulunup ekonomik olan tip uygulanmak için seçilmiştir. Bu kafes sisteme etkiyen dış, yatay ve düşey yükler ele alınıp süper- pozisyon yapılmıştır. En gayri müsait durum için bulunan kesit seçilmiştir. Yüklerin bulunmasında T.S.E.'den faydalanılmıştır. Çatı kafes sistemi, temele ankastre olarak bağlanmış kolonlara, mafsallı olarak birleştirilmiştir. Kafes sistem elemanları basit halde profillerinden oluş maktadır. Temel blokları saksı temel tipinde ve donatılı teşkil edilmiştir. Üçüncü bölümde, çatı ana kirişleri, gergilerle kolonlara asılarak oluşturulan sistem incelenmiştir. Çatı örtüsü ve aşıklar birinci sistemdekinin aynısı kabul edilmiş tir. Gergiler boru profillerinden, ana kirişler basit had de profillerinden seçilmiştir. Çerçeve sistemi idealleştirilerek, Açı Metodu (düğ.nk. hareketli sistem.) yöntemiyle hesaplanmıştır. Çerçeve birleşim noktaları mafsallı teşkil edilmiştir. Dördüncü bölümde ise, yapı sistemlerinin çeşitli bölümlerinde kullanılan çelik malzeme ağırlıkları tablolar yapılarak bulunmuştur. Bundan sistemlerin ekonomik olarak karşılaştırılmalarına geçilmiştir. Ancak burda işçilikle rinde sistemlerin karmaşık ve basit oluşları ile değişebileceğine de değinilmiştir. Ayrıca bu çalışmadan elde edilen sonuçlar özetlenmiştir. Asma çatı sistemi ile kafes sistem yapıları hakkında bir fikir verilmeye çalışılmıştır.
To build a construction that has long span, has been necessary from past to today. New materials and systems has been developed to achieve this problem. The engineer is often concerned with the problem of selecting a truss or a beam to span a given opening. Should not other factors be present, the decision would probably be based on consideration of economy. It is obvious that steel truss and suspended roof systems have more economical result and more strength structure than concrete systems to pass large opening distance where haven't get any basis in the middle of the construction, only the roof truss is supported by two steel column that steel truss rigidly connected to supporting columns. Because of the section of concrete beams increase. depending on rising span and loads. Concrete members has considerable great own weight that cause lots of cost. Steel truss have some advantages so that, chord of truss connected with together like a hinge, so rods of truss only subjected to axis loads. Furthermore These members haven't get bending moment and culting force on them. Braced beam construction, in other words construction with suspended roof also may have economical solution. Because all possible combinations of loads which may logically be applied to a roof, member of systems are subjected to tension force and steel's behaviour is good opposite to tension stress. In addition to when The Weather haven't get strong wind, sections dimension of a member is decrease. Here roof beam is supported by the brace which connected top of the coulmn. The suspension roof provides an excellent method of reducing moment is long-span structures. Here practice, is to erect the roof main beam with its weight being almost carried by the brace. A large part of the loads is transferred by the brace to column, with the result that the amount of bending moment to be resisted by the beam is tremendously reduced. The majority of the load on a suspension roof is carried by the brace in tension, a very efficient and economical method. But, this systems have same disadvantages. These xiii items are discussed briefly below: Surround carrier may- obligate strenghten connection. The system required strong soil codition because of big moment at the bottom of column. And if There is present a soil ankraj. Putting forward in this study, a plain hangar is examined with two different type each other systems. First system's roof is arranged with steel truss and supported each end with column. Second system's roof is formed braced beam to coulmn. Dimension of systems is calculated and importent detail is showen in figure. Each systems have similar properties and design. Covering members are same and Purlins design are like each other. Column and truss distance are five meters. Girts and wind bracing systems are;, exactly like eachother. In addition column where are in the back also similar. Briefly we compare in here two different frame systems. Height of them is selected sixteen meters to enable enlarge the hangar for accommodate bigger plain when if it will be necessary. For enter and exit of a plain to hangar, in front of the building is left open. In this reason classification of construction according to wind forces, it belongs to be not closed structure. Therefore wind force on all surface of building effects with similar forces which have one point two coefficient. In Chapter two, As a preliminary step, it is decided to apply what type of roof truss become oppropriate. Roof truss can be flat or peaked. The flather trusses is prefered for the longer spans. Furthermore two type of truss systems that have different web of chard which eachother is examined. Than these truss is solved under horizantal and vertical loads. Consequently, it is undestood that second type of roof truss is more available to apply. Because A fact which makes it more economical is that most of the members are in tension while those that are in compression are fairly short. And rods of truss where in the second one have lighter force than first one. In addition to at the second truss type has fewer connection point that causes system has fewer rods. For this reason there is less spending on worker costs then first one. The pitch of roof truss is ten percent selected. Before the members of a roof truss can be selected it is necessary for the truss to be analyzed for the different types of loading which can occur. These loads include dead loads, snow and wind loads. A truss will probably be analyzed separetly for each of the different types of loads because all of the different loads will probably not occur at the same time. There are several possible combinations of loads which may logically be applied at the same time to a roof truss. The three combinations listed at the end of this paragraph seem to cover the situation fainly well. The stresses for each member are xiv competed for each of the different loads and combined for each of the combinations given, and the maximum stress for each member regardless of the combination from which it came is used for design. In other words There are three condition of loadig combination. 1- Dead load + full snow load (gravity loads) 2- Dead load +? full snow load + earthquake load. 3- Dead load +. full wind load. After Than it is computed that effect of loads on the building's parts. Purlins are calculated manner of two or three spans beams. The tie of connection of purlins is constituted at the below of section because of don't destroy the form of covering systems. Furthermore roads section of truss are computed and these sections is idealized to three different sections because of easier fabrication. In truss some important tie points which have maximum forces are designed and dimensioned with tie plate. In the column calculating. Column is designed like compression members. Column of end condition code in the bottom is rotation fixed and translation fixed to resist wind force. When translation towards sides of column of the body of the columns is clearly restricted as by diagonal bracing. But there isn't qny members to prevent translation that are toward front or back. For such cases as these column effective lengths can be greater that their actual lengts. Herein we recomended design value when ideal conditions are approximated one point two. At the end of second chapter, foundations are arranged and dimensioned, in addition computed steel rods that are formed in the foundation. Foundation where is at the side of construction is made up like pot shaped because of providing easier stiffness connection between column and foundation. In the third chapter it is examined that roof of hangar is formed by braced beams. In other words roof is suspended by tension brace bars. Braced rods are occured by slindirical pipe. Roof beam is peaked in the middle. The angle where is between braces and beam is selected fourty degree. The systems connection where are between column and beam, beam and braces, braces and column are formed as a hinge with each other. Braces transfers the loads to column, with the result that the amount of bending moment to be resisted by the beams is tremendously reduced. Some members designing in the second systems are similar to first systems. These are roof covering systems, side and roof bracing systems, purlins and column distance. The second system which has braced frames is idealized to simple manner for easier solution. The selected shape of second system is calculated, with method of angle which is xv tie point is movable, under horizental and vertical load which was mentioned before. In the suspended system's column lenght is increased more than system that have truss roof. Because braces connected at the end of column's top. Column where at the back of buildings are similar like a first system. In this case side coulmn of building are computed newly. This Compression member is selected like I shaped section. Than foundation dimension are arranged for transferring load by the column. In the fourth chapter we get out of this tez some conclusion. Firstly Each systems gravity are found out with separetly calculated part of system. In other words apart from each other, all system's part weight are computed. Than between similar part of systems are compared with eachother. In the result of this comperision It can be showen that Roof systems in the first construction is proportion of 3.51 percent less heavy than second one. Though side wall grawity is propartion of 42.49 percent heavier in the second one than first one. Yet in all systems weight first system is proportion of 27.66 percent lighter than second one. At the end of this study some coments are taken out. In the following paragraphy are several further comements which may be of considerable importance for some cases as they pertain to the analysis of suspended and trusses systems. These subjects are discussed briefly below. The designer needs to keep in mind the items causing lower spending without sacrifice of strength. These items which are discussed in more detail throughout the text include the use of standard-size members, simple connec tions and details, and the use of members and materials which will not require an unreasonable amount of mainta- nance through the years. It is seen that first system's weight is less than second one. But fabrication and transportation difficulties need to be considered in selecting the type of systems to be used for a given situation. The smalest amount of meterial will nearly always be used if a truss is selected or spanning a certaing opening; however, the cost of fabrication and erection of trusses will probably be appreciably higher than required for beams. For shorter spans the overall cost of beam (material plus fabrication and erection) will definitely be less but as the spans become greather, the higher fabrication and erection costs of trusses will be more than cancelet by their weight saving. A further advantage of trusses is that for the same amonuts of material they have greater stiffnesses than do beams. In the suspended systems, The roof is supported by the tension braces which connected top of the column. The suspended roof provides an excellent method of reduc ing moment in long span structures. This result bring us all xv i members of the system are subjected to tension stress. Than the steel construction has sussceptible slender member. Therefore if there is compression stress in the structure, structure member is required sections to increase and the use of heavier ones. In addition to on the subject of truss depths, it should be realized that the deeper a truss is made for a given span and loading the smaller will be the chard members, but that with deeper trusses the lenghts of the web members increase. This fact means that the slenderness rations of the web members may become a factor and require the use of heavier members. In the other side suspended system may be preferred type of roof construction from architectural viewpoint. Suspended system may take out same problems on the poor soil conditions because of big bending column moment and this cause expensive foundations. On the other hand systems of trusses roof is lighter and moment is less so soil condition is not as important as suspended ones. Consequently systems that have trusses roof is more economic from weight viewpoint than suspended system but it has lots of fabrication and transportation costs.
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1994
Anahtar kelimeler
Ekonomik analiz, Uçak hangarları, Economic analysis, Aircraft hangars