The research presented in this report is part of a larger analytical and experimental investigation to develop and validate design methods for self-centering concrete columns that inherently have relatively small residual displacements following severe earthquake shaking. The main objectives of this study are to investigate the seismic performance, identify the key design variables, and evaluate the effect of different ground motions and different column configurations for a self-centering reinforced concrete (RC) column with unbonded prestressing strand placed at the center of the cross section.
To achieve these objectives, a series of shak ing table tests and analytical studies were performed. The research was conducted in three phases. First, to develop and validate new refined design methods for self-centering bridge columns, two series of shaking table tests were performed. In the first series of these tests, four cantilever-type partially prestressed reinforced concrete bridge columns with different details were subjected to bidirectional earthquake loading. In the second series of shaking table tests, one two-column bent specimen was evaluated. Second, analytical investigations were conducted to develop and validate analytical methods and models that can accurately capture key performance attributes of conventional concrete columns and unbonded post-tensioned concrete columns under earthquake excitation. In the third phase, a series of parametric studies for self-centering columns was carried out to evaluate the effect of different ground motions and column configurations.
The experimental results demonstrated that the developed self-centering system generally has effective re-centering characteristics after a severe earthquake. This test program demonstrates the substantial benefits of partially prestressed reinforced concrete columns with locally unbonded mild reinforcement and surrounded by a steel jacket. Based on the findings of the analysis, recommendations are made regarding the modeling of RC and self-centering columns. A parametric study using the developed model confirmed the effectiveness of the self-centering system in different ground motions and with different column configurations.
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