الفهرس 
Pocket Connection concept
General scope on the types of precast column-foundation connectionOnly 14 pages are availabe for public view
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Abstract
This thesis presents a theoretical and experimental study of the pocket connections of precast concrete structures. The experimental investigation included seven specimens subjected to vertical and horizontal loads applied at the top of the column with medium eccentricities. The seven specimens are distributed as following; one pilot specimen; Two of the specimens were externally embedded; another two specimens were partially embedded; and the final two specimens were fully embedded specimens. The experimental results indicated the need to revalue the previous design models for this connection. A Strut and Tie design model is proposed for the design of the externally embedded specimens and was adjusted to the experimental results obtained in the presented experimental study and the experimental results obtained from Canha et al. (2007) experimented specimens subjected to loads with large eccentricities. Design charts and design recommendations for the externally embedded pocket connections are proposed to give the values of the forces generated in the pocket walls as a function of the applied forces on the column.
7.2 Observations and Conclusions
Based on the test results of the seven specimens tested in this research and the data stated by other researchers in the literature review, some observations and conclusions were made as follow:
1- Assuming the fully embedded pocket connections are the case of total fixation as the failure happened in the column itself and nothing had happened in the pocket or in the footing, then the partially embedded pockets represented (75% to 90%) of the total fixation case depending on the ratio of the embedded portion of the pocket inside the footing to the whole embedded depth. Finally, the externally embedded pockets represented (50%) of the total fixation case.2- An embedded depth of 1.33h (where h is the bigger dimension of the column) is suitable enough to represent the monolithic specimen in cases of partially embedded and internally embedded specimens.
3- The Partially Embedded pocket connections are the most economic type of the pocket connections to give big flexural capacity.
4- The fully embedded pocket connections are the closest type to represent a monolithic connection where no failure happened in the pocket itself but it is expensive to be used as it requires a big footing depth.
5- from the experimental results, tension stresses appeared on the rear transverse wall which may be resulting from the back-bottom pressure of the column and that’s why the strains monitored on the bottom horizontal reinforcement were very small if compared to the top horizontal reinforcement. According to that a compression strut is introduced connecting the back pressure of the column to the top corners of the pocket walls in the tension side of the pocket.
6- The main vertical reinforcement in the tension side of the pocket walls is more critical in the externally embedded specimens than the partially embedded specimens as the failure happened in the vertical reinforcement and was observed by detachment of the pocket wall located in the tension side of the pocket.
7- The main horizontal reinforcement in the upper one third of the pocket walls is more critical in the partially embedded specimens than the externally embedded specimens as the failure happened in the horizontal reinforcement and was observed by detachment of the four pocket walls from each other at their corners.
8- The behavior of the pocket walls in the externally embedded specimens seems to be monolithic as it behaves as a part of the column until the vertical reinforcement reaches its yield strain then the horizontal reinforcement starts to sustain the loads.
9- The proposed Strut and Tie design model is suitable to represent externally embedded pocket connections subjected to medium and large eccentricities (0.3 ≤ e/t ≤ 5).
10- The proposed Strut and Tie design model for smooth surface interfaces provides the closest predictions of the experimental results.7.3 Recommendations for future work
1- As a result of limited budget for this research program, limited number of specimens was tested with only two different values of embedment lengths. Large number of specimens and test variables have to be experimented and/or numerically simulated in order to provide adequate body of test data for the maximum capacity of the pocket connections and their behavior and cracks pattern.
2- Testing specimens using stroke control cyclic loading machine in order to investigate the post peak behavior of the pocket connection and their behavior under seismic loads.
3- Testing of pocket connections under a wide range of eccentricities to determine the influence of changing the eccentricity of loading on the behavior of the pocket.
4- Testing of the externally embedded pocket connections using the same vertical reinforcement but with different values and configurations of the horizontal reinforcement.
5- Testing of the partially embedded pocket connections using the same horizontal reinforcement but with different values of the vertical reinforcement.
6- Monitoring of the strains of the pocket walls reinforcement using large number of strain gauges and it should be put in the corners of the horizontal reinforcement and at on the vertical reinforcement just above the footing body were the maximum strains in the reinforcement are located.