Performance level thresholds and damage evaluation for composite partially-restrained steel frame–reinforced concrete infill walls with concealed vertical slits

The method to determine the performance level thresholds of partially-restrained steel frame–reinforced concrete infill walls (PSRCW) with concealed vertical slits was presented within the framework of the performance based seismic design. Inter-story drift ratio is selected as a parameter to establish these thresholds based on the relationship between damage state and structural performance level. The damage analysis on the previous test results of PSRCW with concealed vertical slits is statistically investigated to quantify the performance level thresholds using the modified Park–Ang damage index model. The story damage state of a 5-story PSRCW with concealed vertical slits was also examined through nonlinear time history analysis. The maximum average inter-story drift ratio and damage index for this 5-story PSRCW with concealed vertical slits subjected to ten near-fault earthquake waves with velocity pulse were compared with the results from ten far-fault earthquake waves. For frequent and occasional earthquake hazard level, the velocity pulses of near-fault earthquake waves produce the similar damage upon PSRCW with concealed vertical slits in comparison with far-fault earthquake waves. However, for rare earthquake hazard level, the near-fault earthquake waves with velocity pulse cause more severe damage and larger inter-story drift ratio upon PSRCW with concealed vertical slits than the far-fault earthquake waves.