الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
The need to create transfer structures has become an important and necessary matter in many structures; for instance, high rise buildings, which could attribute to the solution of the problems related to the different uses between the upper and lower areas of the building. These transfer structures may be in the form of transfer beams, girders or slabs. Transfer slab is considered one of the most common transfer elements which could exist in high rise buildings. In order to draw a complete picture of this three-dimensional element in this thesis, pile caps are considered as a simple transfer slab. The geometry of pile cap doesn’t provide engineers with a clear understanding of its physical behavior which is considered as a complete disturbed region and there is a very important volume of concrete that is subjected to low normal stresses and significant shear stresses is called ”inactive concrete”, Strut-and-Tie model, on the other hand, can provide this understanding and hence offer the possibility of improving the design. This fact should be reflected in the strength assessment of the nodes and struts. In this study, a three-dimensional nonlinear finite element analysis has been conducted on pile caps that had been experimentally tested and the output results of the cracking pattern, deflection, failure mode and stress distribution from stress trajectories (that can’t be obtained using the strut-and-tie model) are obtained and compared with the experimental results in order to verify the validity of the FEM procedure. The obtained results demonstrates the accuracy and power of the finite element method in dealing with problem of pile caps. The method of strut-and-tie model has been applied to the selected pile caps that had been examined with aid of the finite element. The spatial nature of pile caps has been reflected on the strength of struts and nodes of strut-and-tie model models. The obtained results demonstrate the reliability of the strut-and-tie model method in obtaining a lower bond estimate of the collapse load of pile caps.