Implementation of energy method and evaluation of ductility reduction factors to estimate the seismic response of self-centering structures

Repairing damage caused by residual deformation after earthquakes in common structures is costly. Therefore, self-centering structures have been introduced by researchers to reduce residual deformation after earthquakes. In the typical design of these structures by force method, a constant behavior factor is used to calculate the base shear, which cannot consider the actual performance of the structures. On the other hand, the energy method has more accurate results than the force method by selecting the desirable yield mechanism and target displacement at the beginning of the design process. Since this method has not been used for the analysis of self-centering structures, in this study, for the first time, the energy method was used to determine the seismic response of the self-centering concentrically-braced frame (SC-CBF), and its accuracy was compared with test and analytical results. The results of the study showed that the energy method is a simple and fast analytical method without the need for software modeling and can provide an acceptable estimate of the structural response. By comparing the different ductility reduction relationships, it was observed that the equation presented by Lai-Biggs is the most appropriate relationship with an accuracy of over 80% because they used artificial earthquake records that are close to the design spectrum. Also, the results showed that with increasing the height of the structure, the final rotation and ductility of the structure decreased, which increased the accuracy of the energy method with other relationships to estimate the response of the structure.