Research and application on overall seismic performance evaluation index of frame-core tube structure

The results of dynamic elasto-plastic time history analysis and model shaking table test show that the period variation (stiffness degradation) of each mode is different due to the influence of damage degree and damage location of the structure. The overall seismic performance evaluation index of frame-core tube structures based on the stiffness degradation under dynamic action was proposed as stiffness degradation coefficient and its calculation method was also proposed in this paper, which was verified by shaking table tests of two scale models. The results of test and calculation are in good agreement, and the variation law of stiffness degradation coefficient is consistent. Five frame-core tube models were evaluated and compared by the index, and the results show that the stiffness degradation coefficient increases with the increase of peak acceleration. Under the rare earthquake and over rare earthquake, the stiffness degradation coefficient of the single system model is significantly higher than that of the dual system model, and the model with larger frame-shear ratio has lower stiffness degradation coefficient. It is proved that the dual system exhibits better seismic performance than the single system under the rare earthquake and over rare earthquake, and the model with larger frame-shear ratio has higher overall ductility and seismic redundancy under the same peak acceleration. As the concept is clear, the calculation method is simple, and the evaluation conclusion is consistent with the collapse probability and collapse margin ratio, the stiffness degradation coefficient can be used to evaluate the overall seismic performance of frame-core tube structures.