Yük dağıtma doğrultuları açısından strüktürel formlar

Abstract

Bir binaya etki eden yükler birtakım doğrultular boyunca zemine aktarılmaktadır. Bu araştırmada, binalarda statik yük altında taşıma eyleminin nasıl gerçekleştiği incelenmiştir. Bu amaçla, öncelikle strüktürel sistemler yük dağıtma doğrultuları esas alınmak kaydıyla gruplandırılmış ve herbir sistemin yük dağıtma doğrultusu, yük altında yaptığı şekil değiştirmeler (deformasyonlar) ve form-yükleme büyüklüğü arasındaki ilişkinin ne şekilde değişim gösterdiği incelenmiştir. Sonuçta, yük dağıtma doğrultularına bağlı olarak strüktürel sistemlerin yük taşıma kapasitelerinin ve açıklık imkanlarının farklılıklar gösterdiği görülmüştür.

The structural systems transfer the loads, that have an effect on a building, to the ground. In this way, the transfer of loads dispersal in some directions occur. With this aim, the structural forms can be classified in three groups: 1. The structural forms that disperse the loads in one direction 2. The structural forms that disperse the loads in two direction 3. The structural forms that disperse the loads in three direction. 1- The Structural Farms That Disperse The Loads In One Direction. The load transfer of the structural forms that disperse the loads in one direction, only takes part in a span, uhich is effected by the loads. The other spans don't take part in the action of load transfer. Consequently the action of transfer can not happen altogether. The systems that transfer load in one direction are; 1.1. The Beam Systems 1.2. The Frame Systems 1.3. The Arch Systems -Xll- 1.1. The Beam Systems: The beams are used as horizantal carriers. Mostly they are line-axissed bars which are effected by the vertical loads. In these systems, because of the effect of loads bending (Tensile and compression stresses) and bearing stresses form. In order to prevent the change of shapes, which will form because of these, the form of the system is created so that it can face with these stresses. In the beam systems, related with the used equipment, it's possible to pass 10-30 m. spans-. 1.2. The Frame Systems: The frames are systems which are formed by the compositions of vertical and horizantal bars. These systems are also effected by the stresses of bending and compression. Moreover, as the column and the beam, which are the formers of the system, are tied in a rigid form; these systems can carry more loads when compared with the beam systems. LJith such a system, it's possible to pass 50-100 m. spans. 1.3. The Arch Systems: The arches are oblique-axissed forms which can transfer the loads, that come upon them, with the action of compression to supports. With these systems, the spans up to 100 m. can be passed. In order to form only compression stresses in this system, the form of the system should be created suitable for loading. Consequently the system doesn't have a change on its shape, nevertheless the system changes its shape under the effect of asimetric load. 2. The Structural Farms That Disperse The Loads In Two Directions: The systems which disperse the load in two directions are formed by both line axissed and oblique-axissed carriers. The systems which are formed by planar carriers can be classified in four groups: 2.1. The Grid Systems 2.2. The Plate Systems -Xlll- 2.3. The Folded Plate Systems Z.k. The Flat Truss Systems 2.1. The Grid Systems: The grid systems are formed by two beams, which are right angled to each other; as one beam is put an to the other. In these systems, the action of bending and twisting is the leader of carrying. Because of this reason, the form of the system is created suitable for these effects. With the grid systems, ^0-60 m. spans can be passed in an economical way. 2.2. The Plate Systems: When the height and width of the plates which are car rier elements; is compared with the thickness of them, it's seen that its thickness is lower. In these systems, the load transfer occurs with the combination of bending, shearing and twisting. Consequently; the equipment which forms this system, should be strong. The plate forms are created suitable for the dispersal of stresses in their thickness and the spans, which they will pass. In these systems it's possible to pass spans up to 15 m. 2.3. The Folded Plate Systems: In the folded plate systems, the plates are folded in one or two directions. The load carrying capacity of these systems can increase or decrease according to the height of construction. As the height increases, the dimensions of the span increases. With these systems, it's possible to pass spans up to 1DD m. In the folded plate systems as it is the same in the plate systems, the load is transferred with the action of bending, shearing and twisting. The folded plate behaves as if it's formed of two beams working in a transversal and longitudinal way. As the other systems, the plate forms are formed according to the dispersal of stresses. -xiv- 2.k. The Flat Truss Systems: The flat truss systems are created by the formation of singular bars related to the increasing of the height of the beam. In this way, it's possible to pass spans up to BOm. In light systems in which the height of construction is increased. The form of the system is created with the combinations of simple triangular trusses. The load transfer is provided by the bars which work for compression and tensile. In order to prevent the change of shapes, the bars are arranged suitable for loading. 2.5. The Shell Systems: The thickness of these forms is very little when compared with the height and the width of these forms. They have a duty on transferring superficial loads. As the loads are transferred with tensile, shear and compression the equipment which is used should be strong. As the thickness of them is very little, mostly the bending stresses don't form. Nevertheless if there becomes a sudden changes of section; bending stresses can form. Because of the formation of bending stresses; some changes of shape occurs. Because of this reason, the formation of the shell should be created in a section, suitable for stress values. With these systems, it's possible to pass spans up to 10D m. 3. The Structural Forms That Disperse The Loads In Three Directions: In the structural forms that disperse the loads in three directions, the possibility of spans reaches the maximum level. The principle of activities of these systems, is the bending stresses don't form during the load transfer. These system are; 3.1. The Space Truss Systems 3.2. The Cable Systems 3.3. The Pheonematic Systems -xv- 3.1. The Space Truss Systems: These systems are formed by the arrengement of singular bars in the form of three dimensional modules. Consequently the loads are transferred with the tensile and compression in this system. The form of the system is created according to the regulation Df the loading position of the bars. In this way, the spans up to 150 m. can be passed. 3.2. The Cable Systems: The cable systems are formed by the arrengement of the tensile of steel wires, surrounding on to each other to form cables. In this way, bending stresses can never form in this system. This system is used only for tensile. In this way, the spans up to 1000 m. can be passed. In' the cable systems, in a regular dispersal of loads, changes of shape don't occur. But if a dispersal is made on one side, some changes of shape can occur. 3.3. The Pheonematic Systems: The principle of these systems is to create a difference of compression between the internal and external segments. In this way, the resistance to the external factors is provided. Nevertheless, in order to transfer the load safely, the difference of compression should be kept. The more the difference between the external and internal segments increases, the more the load transferring capacity increases. Consequently it is possible to pass spans up to 500 m.