A macroscopic approach for seismic damage transition within reinforced concrete wall-frame structures

The damage models proposed to date fail to identify the damage transition within one typical dual structural system, that is, wall-frame structures, under strong earthquakes. It's conceptually promising to combine a macroscopic global damage model physically with a simplified structural model that can characterize the interaction mechanism between the frame part and wall part of the structures. Thus, a macroscopic approach, with the integration of a macroscopic global damage model and a generalized shear-flexure coupled model, is proposed to have a closer insight into the damage transition within the wall-frame structures. The relation between the stiffness ratio and the ratio of vibration periods is established by introducing two stiffness-based damage indicators and modal damage indexes. By this relation and the stiffness degradation in the frame part and wall part, the correlations between the modal damages, global damage, and the damages of the two parts are clarified. The combination of the damage indicators of the two parts with global damage is proved to be capable of capturing the damage transition during the dynamic redistribution of internal forces. The case study indicates that the damage predictions of the wall-frame structures are consistent with the interstory drift and proportions of failed components. The comparative study implies the efficiency of strengthening the link beams.