Betonarme çerçevelerin taşıma gücü

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Tarih
1991
Yazarlar
İsmailoğlu, Okan
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Özet
Süper pozisyon ilkesinin geçerli olduğu elastik teoriye göre hesapta, işletme yükünden meydana gelen gerilmeler bulunarak, bu gerilmeler emniyet = gerilmesinden küçük olacak şekilde sisten boyutlandırılır..' Gerçekte ise yapı orantı sınırından sonra da yük taşımaya devam eder. Dış etkiler artıo belirli bir değere ulaşınca yapı kullanılmaz hale gelir yani göçer. Göçme kırılma, burkulma, büyük yer değiştirme, büyük çatlak gibi olayların biri veya birkaçı ile ortaya çıkar. Bu çalışmada malzeme bakımından lineer olmayan sistemlerin göçme yüklerinin hesabı için yük artımı metodu verilmiştir. Lineer olmayan def ormasyonların sistem üzerinde yayıldığı gözönüne alınarak geliştirilen metod, sistemin özelliklerinden bağımsız olup, elastoplastik malzemeden yapılmış bütün çerçevelere uygulanabilir. Dört bölüm halinde sunulan çalışmaların birinci bölümünde konunun tanıtılması, konu ile ilgili çalışmaların gözden geçirilmesi yer almaktadır. İkinci bölümde eğilme momenti ve normal kuvvet etkisindeki çubuklarda kesit tesini-şekil değiştirme bağıntıları çıkarılmış ve bu değerlerin hesabı için bilgisayar programı hazırlanmıştır. Üçüncü bölümde bir önceki bölümde hazırlanan bilgisayar programı ile farklı yatay yükler altındaki çerçeveler çözülerek bu çerçeveyi mekanizma durumuna getiren yükler bulunmuştur. Son bölümde bilgisayar programı ile elde edilen çıkışlar gözden geçirilip değerlendirilmiş ve ulaşılan sonuçlar açıklanmıştır.
The ain of structural engineering is to realize structures which provide both safety and economy conditions. It is known that these two main factors have considerable effects on each other. Before the use of computer technology in structural engineering, safety factor was the most important factor in the design of the indef initeness in the real behaviours of the structures. Up to date, by reason of both economic conditions and uncommon use of computer technology in structural engineering, structural engineers were used to design structures which have economy factor payment in advance. It is clear that, to realize this thought, the structures have to be designed by nathods which consider both material and geometrical non-linearities. In this study, a method of load increasing is presented for the determination of the collapse loads of non-linear elastoplastic structures. The non-linear deformations are taken into account as distributed continuously over the structure. The method is independent of the characteristics of the structure; hence is applicable to the elastoplastic framed structures of arbitrary shape. If the Elastic Theory is used, the superposition rule is apnlied. Stress from service loads roust be smaller than the allowable stress. In fact, the system is carried the loads after the estimated boundary. But, when the exterior loads is reached a current value, the systen is subsided. In the first chapter is an introduction of the subjcet. In the second chapter, deflection relations of the rectangular reinforced concrete rods which are loaded by bendin» moment (H) and normal force (N), are obtained. In plactic design, the ultimate strength considered is that which brings the frame to the verge of failure or collapse, as suming perfect plactic hinge action. A member cannot collapse under moment loading (except for buckling) until there are enough actual or plastic hinges to transform it into a mechanism. If number of plastic hinges is more than degree of hyperstatical of frame, mechanism takes form. If number of plastic hinges is equal to degree of hyperstatical of frame, Mechanism cannot takes form yet. When the subsequent plastic hinge takes form, the frame collapses and mechanism takes form. Plastic hinges absord energy which external loads produce. He may collect plastic deformation at any one point. Then plastic hinges generally may take form the places which moments have got the bigger value or singular loads exist on the frame; moreover on the crucial point. If all possible mechanism are investigated, the lowest load factor will be the true one or true collapse load. The building in shape.3.1.. is reduced the frame which shows same behaviors by applying same external force in shape -VI- 3.2. After using the method of load increasing, the collapse loads are found. These loads are earthquake or horizontal loads. At the beginning by taking earthquake loads which were found by using static method is started for loading. After, in other steps, these loads are increased proportional. In the third chapter, these loadings can be seen. Plastic hinge may be existed on the member of frame in two different conditions. One of these conditions is that; if extension of steel in reinforced concrete member is equal 0,01 or much, i.e AT £ 0,01 for steel. The other one; If shortening of concrete in reinforced concrete member is equal 0,003 0,0035 or much, i.e G = AT j- * 0,003 ~ 0,0035 for concrete The reduced frame is divided members. After every loading, bending moment (M) and normal force (N) of members of frame are found. Moreover movements which in same direction with loading of crucial points are found. Firstly, the frame is solved by program named 0KAN 23. This program calculates bending moment (M) and normal force (N) for each rod. Moreover this program calculates movement of crucial points of frame. Input datas for this program are: 1- Coordinates of crucial points of frame. 2- Left and right crucial points oof roads. 3- Loads which force to the frame horizontally and vertically, 4- Points which these loads act. 5- Rijidities of bending of reinforced concrete rods. 6- Rijidities of extensions of reinforced concrete rods. -VII- Secondly, program named OKAN1? calculates deflections of the rectangular reinforced concrete rods which are loaded by bending moment (M), and normal force (F). Moreover, this program calcutes new rijidity of bending of rod and new riiidity of extension of rod. Moreover, this program calculates shortening of concrete and extensions of steel. Input datas for this program are: 1- Fields of steel of rectangular reinforced concrete rods. 2- Prism resistance of concrete. 3- Steel stress at the instant which steel starts to flow. 4- Width of cross section of reinforced concrete rod. 5-Lengtb of cross section of reinforced concrete rod. 6- Quantity of normal force. 7- Quantity of bending moment. 3- Value of module of elasticity of steel. 9- Proportion of mistake for normal force. 10- Proportion of mistake for bending moment. 11- Value of SI 00 ahd given distance for rust. 12- Rijidities of bendings and extensions. If S100 is given 1. at input datas, rijidities of bendings and rijidities of extensions are given as datas in input datas. If Si 00 is given a number except 1., then 0KAM5 calculates them oneself. At every loading, in program named OKAN23, as datas, new rijidities of bendings and new rijidities of extensions afe" given. Because rectangular reinforced concrete rods cracks by rotation. Therefore", value of rijidities of bendings of rods and value of rijidities of extensions of rods become less. First 0KAN5 calculates rotation of rod (X) and unit du ds extension of rod ( du -^ -VIII- After, 0KAN5 calculates rijidity of bending of rod and rijidity of extension of rod by using these formulas; ; ET = -4=- EI d\i N - in? = N d s EF ' ",l \chT ds Relation of bending moment-rotation consist of thre? separate region for reinforced concrete rods which are forced by bending moment. We can see that at shape 2.1. These regions: LQ = The situation which cracks starts to take form at the outside Dull fiber of reinforced concrete cross section. L, = The situation which plastic form change starts to take form at the steels which pull forces act on it or outside pressure fiber of concrete. L7 = The situation which the bending moment equals to maximum carrying capacity of cross section by increasing. This is value of plastic moment. It is represented Mp. Therefore, concrete in pressure region is crushed and broken or steels which pull force act on it are broken. L situation: o Relation of stress-deformation (
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1991
Anahtar kelimeler
Betonarme, Betonarme çerçeve, Taşıma gücü, Yatay yükler, Reinforced concrete, Reinforced concrete frame, Bearing capacity, Horizontal loads
Alıntı