الفهرس 
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Abstract
In the current study, a new innovative column technique is proposed to overcome the issues of the brittleness of conventional RC columns as well as the durability problems due to the permeability of concrete which causes corrosion of steel, especially when exposed to a chloride environment. The new composite columns consist of SHCC reinforced with longitudinal and lateral reinforcement to perform a prefabricated tube and then filled with concrete. These columns were tested under concentric and eccentric load schemes. The innovative proposed column is a promising technique in the construction and confinement of columns. The SHCC tube is expected to improve the overall performance of the column in terms of modes of failure, ultimate axial capacity, ultimate flexural capacity, and durability. In addition, the SHCC tube is expected to provide a confining pressure to the concrete core, which increases the ductility as well. This research consists of seven chapters; Chapter (1) is the introduction which presents the problem statement, methodology, and organization of the work in the current thesis. Chapter (2) presents a literature survey on the conventional methods of construction as well as the strengthening methods to improve the strength, ductility, and durability of columns. In addition, a detailed review on the different properties of SHCC and the motivation for using it in the structural elements, especially in construction of columns. Chapter (3) presents a summary of column confinement principles as well as the different techniques of confinement for RC columns. Chapter (4) demonstrates the research methodology. The materials used in the experimental program, as well as the specimen configurations, testing setup, and instruments, are all described. According to the studied parameters, the experimental study consisted of three main phases: The first phase, I, is conducted on columns with square cross-sections of dimensions 200×200mm divided into four groups. Whereas the second phase, II, is conducted on columns with circular cross-sections with diameters of 200mm divided into four groups. The third phase, III, is conducted on beams subjected to four-point loading under bending tests; that phase is divided into two groups of beams; one group is beams with square cross-sections of dimensions 200×200mm and the other group is beams with circular cross-sections of diameters 200mm. The first and second phases (I and II) are concerned with studying the behavior of concrete-filled SHCC tubular (CFSHT) columns, which is the subject of this thesis. The third phase III is concerned with studying the flexure (CFSHT) beams behavior that is required for analytical study. Different parameters are considered in phases I and II, such as eccentricity ratio and longitudinal and lateral reinforcement ratios. Chapter (5) presents the experimental results of all test specimens. The modes of failure, the ultimate loads, the load-deformation curves, the developed strains for the longitudinal and the lateral reinforcement, and the ductility of the specimens are listed and discussed. Chapter (6) presents a numerical simulation for the behavior of the proposed columns using a finite element program (ABAQUS). Chapter (7) presents a proposed equation for predicting the capacity of the CFSHT columns under concentric loading taking the confinement of VII lateral ties and SHCC into consideration, as well as an analytical investigation on the moment-load, P-M, interaction for the innovative columns. Chapter (8) summarizes the key conclusions extracted from the current study. Recommendations for further investigations on the structural performance of the proposed innovative column are also suggested In the current study, a new innovative column technique is proposed to overcome the issues of the brittleness of conventional RC columns as well as the durability problems due to the permeability of concrete which causes corrosion of steel, especially when exposed to a chloride environment. The new composite columns consist of SHCC reinforced with longitudinal and lateral reinforcement to perform a prefabricated tube and then filled with concrete. These columns were tested under concentric and eccentric load schemes. The innovative proposed column is a promising technique in the construction and confinement of columns. The SHCC tube is expected to improve the overall performance of the column in terms of modes of failure, ultimate axial capacity, ultimate flexural capacity, and durability. In addition, the SHCC tube is expected to provide a confining pressure to the concrete core, which increases the ductility as well. This research consists of seven chapters; Chapter (1) is the introduction which presents the problem statement, methodology, and organization of the work in the current thesis. Chapter (2) presents a literature survey on the conventional methods of construction as well as the strengthening methods to improve the strength, ductility, and durability of columns. In addition, a detailed review on the different properties of SHCC and the motivation for using it in the structural elements, especially in construction of columns. Chapter (3) presents a summary of column confinement principles as well as the different techniques of confinement for RC columns. Chapter (4) demonstrates the research methodology. The materials used in the experimental program, as well as the specimen configurations, testing setup, and instruments, are all described. According to the studied parameters, the experimental study consisted of three main phases: The first phase, I, is conducted on columns with square cross-sections of dimensions 200×200mm divided into four groups. Whereas the second phase, II, is conducted on columns with circular cross-sections with diameters of 200mm divided into four groups. The third phase, III, is conducted on beams subjected to four-point loading under bending tests; that phase is divided into two groups of beams; one group is beams with square cross-sections of dimensions 200×200mm and the other group is beams with circular cross-sections of diameters 200mm. The first and second phases (I and II) are concerned with studying the behavior of concrete-filled SHCC tubular (CFSHT) columns, which is the subject of this thesis. The third phase III is concerned with studying the flexure (CFSHT) beams behavior that is required for analytical study. Different parameters are considered in phases I and II, such as eccentricity ratio and longitudinal and lateral reinforcement ratios. Chapter (5) presents the experimental results of all test specimens. The modes of failure, the ultimate loads, the load-deformation curves, the developed strains for the longitudinal and the lateral reinforcement, and the ductility of the specimens are listed and discussed. Chapter (6) presents a numerical simulation for the behavior of the proposed columns using a finite element program (ABAQUS). Chapter (7) presents a proposed equation for predicting the capacity of the CFSHT columns under concentric loading taking the confinement of lateral ties and SHCC into consideration, as well as an analytical investigation on the moment-load, P-M, interaction for the innovative columns. Chapter (8) summarizes the key conclusions extracted from the current study. Recommendations for further investigations on the structural performance of the proposed innovative column are also suggested.