الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Pile cap is a reinforced concrete structural slab utilized to distribute a column load to a group of individual piles. As a result pile caps are an important structural element, and are basic for safety of the structure, and usually not open to visual inspection under service, a conservative design is justified. Complete analyses are complex, and allowable values for use in design are not available in building codes for certain modes of failure. As a result, most pile caps are designed to in practice by various short-cut rules of thumbs. Moreover, the soil existence is important to obtain the real behavior of pile caps. In this thesis, the most common methods for designing pile caps are presented, which are the beam method and the strut and tie method. The first method (Beam Method) is recommended by ACI [1], CRSI [21], British [11], and Egyptian Codes [44]; while the second method (Strut and Tie Method) is recommended by the Canadian Code [14]. The results obtained from the previous experimental, and numerical studies performed on pile caps are also presented, to highlight the factors that have been taken into consideration, the factors that have been ignored, and the effect of these factors on the behavior of the pile caps under different loading cases. To obtain the real and exact behavior of the pile cap, a nonlinear finite element analysis was carried out on 36 pile caps to examine the pile cap behavior under static vertical loads developed due to changing pile-soil-pile cap parameters which are; piles embedded length, piles diameter, piles spacing, and pile cap depth. It was recommended from previous numerical analysis performed on pile caps, that the material modeling for both soil, and reinforced concrete should be taken to be nonlinear during the loading history. The results of the study was presented as a comparison between pile caps where at first the effect of pile cap thickness is presented, the effect of piles diameter, the effect of piles spacing, and finally the effect of piles embedded length is presented. Each of these effects is presented by comparing the pile cap cracking load, pile cap settlement, normal stress distribution, shear stress distribution, normal soil stresses directly under the pile cap, and axial stress in reinforcing steel bars of each case. from this parametric study, it can be concluded that the beam method represents the nearest behavior of the actual behavior of the pile cap under working conditions, but it still needs some modifications to represent the soil existence. Another important notice that should be drawn, that the soil plays an important rule in the distribution of the internal stresses and changes extensively the pile cap cracking loads and the pile cap settlements. Modifications to the beam method still required that the effective cap width should be reduced because the internal stresses in the edge distance equals almost zero. It can also be noted that the pile cap behavior changing from thin plate element to a thick plate behavior depending on the pile cap depth, so spreading reinforcement along pile cap width represents the best reinforcement layout for reinforcing pile caps. Moreover, the reinforcing steel bars predicted form the beam method, should be reduced because the axial stresses in the reinforcing steel bars do not reach 70% of their yield stress.