Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı 2

Analysıs of Axıally Symmetrıc Shell Structures
Shell structures are quite economical and extremely safe structures in terms of materials and such reasons as extremely small thickness compared to other dimensions, the suitability of the system geometry to convert stress distribution into pressure stresses, ability to minimize the effect of bending. Although the construction technologies and material properties have been changing, they have been preferred for aesthetical reasons for centuries. They are also preferable for spanning large areas and/or close them with extreme structural safety, besides they can be designed in many different geometric properties in terms of aesthetics and applicability. It is possible to design them in many different geometric properties for purposes like aesthetics and applicability besides common geometries such as dome, arch, hyperbolic paraboloid, cylinder. The most common geometric shapes are formed by spherical dome, cylindrical wall, circular plate and combinations of circumferential beam elements. Shell structures, which are commonly used in construction of structures that have importance in terms of building and function, are considered to be within both geometrically and mathematically complex structural systems in terms of the exact mathematical solution. This situation causes various assumptions to be made in order to find the solution of mathematical expressions or leads to the investigation of alternative solutions. Nowadays, computer programs that are running based on finite elements and sometimes finite difference formulation are preferred for the analysis of such structures. However, problems such as exceedingly large number of unknowns and the volume of transactions, the difficulties in the preparation stage for mathematical model, the inability of results for sufficient detail of the design, impracticality of optimization are experienced in analysis with this method.
In the present study, first, a practical method associated with the usage of the finite element method for analysis of the axially symmetric shell structures are presented especially for problems in which transaction volume is intensive. With the help of this method, it is possible to prepare a more detailed mathematical model and get more detailed analysis results with less unknowns. Then, two separate computer programs, which are developed with the usage of classical shell theory and shell theory formulations of flexibility method as an alternative to the finite element method, are presented. These two computer programs that are developed in the current study and named as “ESKA-2” and “ESKA-4” (Axially Symmetrical Shell Analysis) make the analysis of axially symmetrical shell structures with two and four integration constants. Two integration constants are used in the formulation of ESKA-2, in which the interaction within the top or bottom parts of the wall is not considered. It is possible to obtain correct analysis results with this computer program if the criteria of walls to be high enough is fulfilled since there will not be interaction between the top and bottom parts. On the other hand, ESKA-4 is formulated with four integration constants, and gives the correct results without the need for any criteria to be fullfilled. With the help of these two programs; the conditions, for which long walls criteria is valid, are also investigated in this present study. The advantages of the two methods are discussed with numerical examples too.


BAHÇEÇİ Ayşenur

Danışman : Doç. Dr. Cevza Melek KAZEZYILMAZ ALHAN

Anabilim Dalı : İnşaat Mühendisliği

Mezuniyet Yılı : 2014

Tez Savunma Jürisi : Doç. Dr. Cevza Melek KAZEZYILMAZ ALHAN

Prof. Dr. Hafzullah AKSOY

Doç. Dr. Betül SAF

Doç. Dr. İlknur BOZBEY

Doç. Dr. Sadık ÖZTOPRAK