Yapı sistemleri hesap yöntemlerinin karşılaştırılması boşluklu perdelerin yatay yükler altında çözümü
The Comparison of the caluculation methods of structural systems and the shear walls with openings calculation with finite elements method
- Tez No: 19331
- Danışmanlar: DOÇ.DR. SUMRU PALA
- Tez Türü: Yüksek Lisans
- Konular: İnşaat Mühendisliği, Civil Engineering
- Anahtar Kelimeler: Boşluklu perdeli sistemler, Sonlu elemanlar yöntemi, Yapı sistemleri, Yatay yükler, Çerçeve sistemi, Coupled shear systems, Finite element method, Structure systems, Horizontal loads, Frame system
- Yıl: 1991
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
ÖZET Yüksek lisans tezi olarak yürütülen bu çalışma esas itibariyle iki bölümden oluşmaktadır: Birinci bölüm, düzlemi doğrultusunda dış yüklerin tesirinde bulunan değişken enkesitli elemanlara sahip üç açıklıklı bir çerçeve sisteminin; çeşitli yüklemeler al tında değişik hesap metodları ile hesaplanması ve boyutlandırılmasının yapılması problemidir. Bu amaçla önce çerçeve sisteminin bir ön boyutlandırılması yapılmıştır. Bundan sonra değişik yüklemeler ve dış tesirler altında, değişik metodlarla sistemin çözümü yapılmıştır. Bu çözümlemelerden sonra elde edilen en elverişsiz kesit tesirlerine göre, yapının kesin boyutlandırılması yapılmıştır. Bu esnada çeşitli yüklemeler ve bu yüklemeler için kullanılan hesap metodları sırasıyla; ön boyutlandırma ve sabit yükler için Oçı Yöntemi, verilen ilave yükler için Matris Deplasman Yöntemi, yatay yük için Cross Yöntemi, düz gün sıcaklık değişmesi için Matris Kuvvet Yöntemi, mesnet çökmeleri için Cross Yöntemi ve Endirect Deplasman Yöntemi ile iki kesit için M, N, T tesir çizgileri çizilmiştir. ikinci bölümde; üç katlı antimetrik yüklü, simetrik bir boşluklu perdenin, önce Sonlu Elemanlar Yöntemi ile hesabı yapılmıştır. Daha sonra aynı sistemin fiktif bir çerçeve gibi ele alınıp, kirişlerin perde içinde kalan kısımlarının perde kenarından ne kadar uzaklıkta sonsuz rijit alınabile ceğini gösteren çeşitli X uzunluklarına göre fiçı Yöntemi ile çözümü yapılmış ve elde edilen sonuçlar Sonlu Elemanlar Yöntemi sonuçlarıyla karşılaştırılmıştır.
Özet (Çeviri)
THE COMPARISON OF THE CALCULATION METHODS OF STRUCTURAL SYSTEMS AND THE SHEAR WALLS WITH OPENINGS CALCULATION WITH FINITE ELEMENTS METHOD SUMMARY In its historical development“the structural elements”has made comprehensive progress. The thick columns of older days has leaved instead of the columns as 10 or 15 times thinner than the older ones. The two reasons for that are the development of methods of calculation and the utilisation of some new methods that was not easy to be used before. The investigation of structures by engineers has two * purposes: a) Structures to be built must be safe enough b) The cost of the structure must stay in economical 1 i m its. The safety factor is no more desirable without economi- city. Today we are proceed that some indefinite systems are being calculated in paralel to the development of structural engineering in our country. This study which has been carried out for M. Sc. thesis, consists of two main chapters. In the first chapter, the analysis of a three span rein forced concrete plane frame subjected to various external effects is presented. Various structural methods have been used for each external effect. Thus, the applications and comparison of the methods have been illustrated. The preliminary cross-sectional dimensions of the frame, ine preliminary cross-sectional dimensions or trie -rrame have been designed thru utilization of the Slope-Deflection Method. As a result of this part, a sufficient result can b obtained in pre-designing of structural systems as decreasin the characteristic resistances of the material in some portions and as considering only the dead weight has shown <vi)In the second part of this chapter, the structure is analysed by Slope-Deflection Method for dead weight acting alone on the structure. In Slope-Deflection Method, the unknowns are the rotations of joints and the independence displacements of the ends of members forming the system. In this method, the equation can be obtained automatically. In the third part of this chapter, the structure is analysed by the Matrix Displacement Method for live loads acting on the structure. In Matrix Displacement Method, unknowns are the dis placements of joints forming the structural system. This method enables to operate with lesser unknowns in systems having more members connected to joints forming the system. Equations can be obtained automatically. But, when the equations are not good in stability, returning is restricted because of the lackness elasticity in choosing unknowns. In the fourth part of this chapter, the structure is analysed by the Cross Method for lateral loads. In Cross Method, the unknowns are the rotations of joints and the independence displacements of the ends of members forming system. In symmetrical structures, it is possible to use half of the unknowns when the loads are symmetrical or ant isymmetrical. Because of the given loads are not in this way, the loads have changed into a places of symmetrical and ant isymmetrical parts. It has shown that the results can be get more quick and easily by using this way. In the fifth part of this chapter, the uniform tempe rature changes had taken into account as an external effect on the structure changing at the upperside and under side of the crosssect ion. Because of this effect some reactions acting on the cross-section is expected. To determine these reactions, the structure is analysed by Matrix Force Method. In Matrix Force Method, the unknowns are the forces acting at the ends of the members which have formed the structure. This method enables to operate with lesser unknowns in systems which having more members in frames forming the system. fls the last statical calculation method for this study, the structure is analysed by the Cross Method for different support settlements as an external effect. Structural (vii)systems are expected to have support settlements during its lifetime. If these settlements are same on every support of system, there will not be any reactions acting on structures members. But if they are different, some reactions acting on the structures cross-sections are expected. fit the end of these calculations, the dimensions of the critical cross-sections obtained from the preliminary analysis are checked under the most unsuitable loading conditions which considers different external effects action in some proportions. With this study, it is seen the combinations which give the most unsuitable cross-sectional react ions. In the first chapter, finally, the influence lines for bending moment, axial force and shear force of two given cross-sections are obtained by means of Indirect Displacement Method. In the second chapter, the shear walls with openings which have certain properties are estimated by using both the finite element method and an approximate method for the analysis of structure composed of frames and walls with openings called Wide-column analogy. Simply stated, a shear wall is a column whose characte ristic dimension is large compared to the overall dimensions of the frame, ft shear wall-beam system in effect has rigid zone dimensions much larger than in a beam-column system, thus necessitating that finite dimensions of the member be considered in order to properly reflect the behaviour of the system. The earliest investigations of shear walls used the concept of equivalent frame, and today this method is still one of the most popular methods for the solution of practical problems. In essence, the method considers walls and beams as interconnected line elements, the aggregate behaviour being simulated by an equivalent frame. In comparison to a plane frame consisting of columns of normal proportions, the wide- column frame, as the name implies, attempts to copture the additional stiffness of the system due to the relatively large widths of shear walls. It is seen that the rotation of the wall at its center of gravity produces not only rotation at the and of the connecting beam but also a vertical displacement, this effect is accounted for in the wide-column frame by considering that portion of the beam between the center of gravity of the wall and intersection of beam and wall to be infinitely rigid. ( vi i i )The wide-column analogy is very popular in design offices because the analysis can take into account such items as nonuniform floor heights, varying beam or slab stiffness, varying wall geometry, loading conditions elastic support at bases, etc. A method of solution known as the Finite Element technique is being increasingly used for the solution of such problems. Although the finite element method is based on the idea of discretisation, the technique recognises the structure as a continuous body and provides solutions not only at a finite number of discrete points but also at all other locations in the structure. One of the finite element method is the ease with which boundary conditions can be incorporated into the technique. Kinematic boundary conditions in terms of displacements and rotations are easily introduced into the assembled equations without reqiring special techniques, the method can accomodate complex geometry and boundary conditi ons. The technique is quite general and can be applied syste matically to solve a wide range of structural engineering problems. The finite element method possesses certain characteris tics that take advantage of special computer techniques in that it can be systematically programmed to take into account complicated loading and boundary conditions. The finite element method essentially consists of: 1-Ideal i zat ion of the structure into an assemblage of discrete elements. E-Selection of displacement function. 3-Evaluation of stiffness of each element from it is geometric and elastic properties. 4-Assembly of the overall stiffness matrix from indivi dual element stiffness matrices. 5-Modif ication of stiffness matrix to take into account boundary conditions. 6-Solution of resulting equilibrium equations to obtain nodal displacements. 7-Calculat ion of stresses. The finite element solutions would give a better estimate of stress near points of stress concentration and an improvement in accuracy can certainly be obtained by reducing <ix)the size of the element mesh. It should be borne in mind, however, that the order of solution will normally be much grater than by wide-column frame and the latter solution is to be preferred for regular problems where concentration effects are not to be considered. If the connecting beams are very slender, however, the local deformations at their ends can cause significant error in the frame solution and in such cases the second order elements give comparatively better results. In this study, first, the displacement of the shear walls with openings which is given are calculated by using finite element method. In the second, the system is idealized as a wide-column frame which has infinitely rigid zone, and the wide-column system >s calculated for the different lengths X by using Slope-Deflection Method, fit the end of this study, the results of calculations both the finite elements method and the wide-column frame system are compared with. (x>
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