Effect of In-plane Discontinuity Irregularity on the Seismic Fragility of RC Frame Shear Wall Structure Strengthened with Concrete Jacket

In RC structures, it is possible to move the shear wall due to architectural factors such as creating entrances for parking, creating openings, changing uses and other factors, which leads to in-plane discontinuity. According to recent studies, this irregularity can lead to weakness in the seismic response of RC buildings. In this type of irregularity, the beam above the transferred shear wall will be the focus of failure. In this study, a 9-story RC frame shear wall structure is modeled nonlinearly. Then, by applying different scenarios of in-plane discontinuity irregularity and strengthening the beam above the transferred shear wall with a concrete jacket, the seismic fragility curve of regular and irregular frames have been developed based on the results of incremental dynamic analysis. The near and far-field ground motion records used in the time history analysis of the frames are selected based on the conditional spectrum. Also, to consider the effect of irregularity on the damage limit states, the pushover analysis of the frames has been done. Results indicate that by strengthening the beam above the transferred shear wall, the seismic fragility of the irregular frames has decreased in most cases compared to the regular frame. Also, results show that in irregular frames, the median peak ground acceleration in the two-story shear wall transfer case for different damage limit states is 19% higher than the one-story transfer case to the side spans. Also, the median peak ground acceleration in the state of transition of the shear wall to the adjacent span for different damage limit states is 15% higher than the state of transition to the far span.