Hysteretic energy distribution model of CFDST composite frame with metallic dampers using coupled shear-flexural beam model

Abstract

Novel steel–concrete composite structures have drawn increasingly attention in recent years especially in high-rise buildings owing to its superior structural performance over conventional concrete and steel structures. Moreover, energy dissipation devices such as metallic dampers and buckling-restrained braces (BRB) were necessarily added in this type of structure to resist seismic loads. However, the existing research regarding to the dual system consisting of composite frame and energy dissipation was limited. In this paper, the dual system consisting of concrete-filled double skin steel tubular (CFDST) composite frame and metallic damper was set as the research subject, especially focusing on the analysis of hysteretic energy distribution along the height. The 10- and 20-story dual systems were designed with different parameters revealing the influence of semi-rigid connection and metallic damper. Nonlinear models of structures established by Opensees software were validated by the test results. Afterwards, the energy distributions of all stories were discussed. It demonstrated that the metallic damper could absorb considerable energy under seismic loads while a semi-rigid connection with relatively high moment strength had a detrimental effect on the column. Moreover, the semi-rigid connection in the span without metallic damper in high story exhibited significantly larger rotation than that in the span with metallic damper. Finally, the method to estimate the energy distribution estimation of the dual system was developed, in which the lateral displacement pattern was observed by the coupled shear-flexural beam model to fully consider the flexural deformation of the dual system. An equivalent distribution of the shear and bending stiffness was also proposed considering the effect of the semi-rigid in the span without metallic damper. The predicted results from the model were validated by the analysis results derived from the nonlinear model. The theoretical and analytical results of the paper could activate the application of the dual system and provide a reasonable method to estimate the hysteretic energy distribution of the dual system.