RESEARCH ON THE DESIGN METHOD OF REASONABLE REINFORCEMENT RATIO OF ENERGY-DISSIPATION BARS IN SELF-CENTERING COLUMNS

In recent years, self-centering columns have drawn more and more interests from researchers, due to their self-centering capacity. The unbonded prestressed rocking columns without energy dissipating devices have small energy dissipation capacity, which leads to large displacement response under the earthquake. The energy-dissipation bars are generally applied at the rocking joints of self-centering columns to improve the energy dissipation capacity of the columns. The research results show that: increasing the number of energy-dissipation bars can increase the energy dissipation capacity of the columns, while the residual deformation of them increases. The reasonable reinforcement ratio of energy-dissipation bars is less involved in existing research. A numerical investigation is conducted by the grounds of the nonlinear time-history analysis to determine the influence of the performance index λ on the seismic performance of self-centering columns. And a design method for the reasonable reinforcement ratio of energy-dissipation bars in self-centering columns is proposed by the combining the relationship between the reinforcement ratio of energy-dissipation bars and the performance index λ. The reasonable energy-dissipation bar reinforcement ratio of self-centering columns with different periods can be obtained through the recommended value of λ and the relationship of ρ-λ. A four-span continuous beam bridge with a reasonable reinforcement ratio is selected as a case to verify the validity of the proposed design method. The analysis results show that: when the structural period ratio η<1.0, the recommended value of λ is 1.2. And the recommended value of λ is 2.0 for the structural with period ratio 1.0\leqslant η\leqslant 2.0. When the structural period ratio η>2.0, the reasonable energy-dissipation bar reinforcement ratio of 0.5% is proposed.