Browsing by Subject "Columns, Concrete--Testing"
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Item Non-destructive evaluation of gravity load carrying capacity and lateral load damage of reinforced concrete slab-column connections(2006) Argudo, Jaime Fernando; Jirsa, James O.Item Seismic performance of full-scale reinforced concrete columns(2005) Bae, Sungjin; Bayrak, OguzhanThe deformation capacity of a concrete column can be expressed by using different ductility parameters such as curvature ductility, displacement ductility or drift capacity. However, little research has been conducted into the relationship among different ductility parameters. The objectives of this research are (1) to investigate the relationship among various ductility parameters by considering the effects of shear spanto-depth ratio and axial load level and (2) to develop methods and procedures that can be used to estimate the deformation capacity of reinforced concrete columns. Five full-scale reinforced concrete columns were tested at The University of Texas at Austin. Test results indicated that the shear span-to-depth ratio and axial load level were important parameters influencing the relationship among various ductility parameters. Measured plastic hinge lengths of column specimens were also affected by the shear span-to-depth ratio and axial load. The plastic hinge length of concrete columns was investigated by studying the compressive strain profile of the core concrete. An analytical procedure was used to study the effect of various parameters on plastic hinge length. Based on the results of the experiments and a parametric study, a new expression that can be used to estimate plastic hinge lengths was proposed. Two methods that can be used to predict the deformation capacity of reinforced concrete columns were developed. One of these methods can be considered as a state-ofthe-art analytical method, which employs various phenomenological models for confinement of concrete, reinforcing bar buckling, reinforcing bar slip and shear deformations. The other method consists of simple expressions derived by studying the lateral load response of columns as influenced by the P-Δ effect. The use of the rigorous analytical method provided reasonably accurate estimates for the deformation capacity of over one hundred columns tested by various researchers. The use of simple expressions, on the other hand, traced the lower-bound of the measured drift capacities of these columns. The simple expression is recommended for use in performance-based design of reinforced concrete columns.Item Use of CFRP to provide continuity in existing reinforced concrete members subjected to extreme loads(2008-08) Kim, InSung; Jirsa, J. O. (James Otis); Bayrak, Oguzhan, 1969-A special problem in many reinforced concrete structures built in the 1970s and earlier is the lack of continuity between elements. Continuity is a characteristic of structures essential to preventing collapse. Therefore, in extreme loading conditions such as loss of a column support due to terrorist attack or if earthquake or other extreme actions occur, the structures could be vulnerable to collapse. The study reported here focused on two structural discontinuities in existing reinforced concrete structures, discontinuity in bottom reinforcement in beams (horizontal discontinuity) and poorly detailed lap splices in columns (vertical discontinuity). The objective of this study was to develop rehabilitation methods using CFRP to provide continuity of reinforcement in existing structures. To develop the rehabilitation methods, two separate experimental studies were conducted using beam and column specimens. CFRP materials were applied to the bottom or side face of a beam and anchored using CFRP anchors or U-wraps to provide horizontal continuity in bottom reinforcement and tested under dynamic loading. After CFRP rehabilitation, the ductility of the bottom reinforcement and large rotational capacity of the beam were realized. CFRP materials were also applied to the lap splice region in square and rectangular columns which exhibited a brittle splice failure as-built. After rehabilitating the columns using CFRP jackets and anchors, the failure mode changed from a brittle splice failure to yield of column reinforcement, and the strength and deformation capacity were improved under both monotonic and cyclic loading. Based on the results of beam and column tests, design guidelines for CFRP rehabilitation were proposed. Horizontal and vertical continuities can be provided through the use of CFRP for rehabilitating existing reinforced concrete structures that were designed prior to the introduction of codes that require continuous reinforcement along members and between adjacent members. The vulnerability of such structures to collapse can be reduced through rehabilitation.