## 3 Damage Indexes Effectiveness
### MSA Results
However, their efficiency decreases for LS and CP due to significant overlap O2 between 25% and 55%, accompanied by an increased dispersion over 20%. The B-V and P-A indexes maintain their high efficiency for UPD, as they have no overlap O1 and scatter values between 1% and 15%. However, their reliability decreases for LS, CP and GC, with overlap O2 increasing from 5% to 80% and dispersion values increasing from 20% to 65%. Similarly, the P-Al index for UPD has a minimum dispersion from 5% to 10% and no overlap O1, but its efficiency decreases for LS, CP and GC due to a larger overlap O2 ranging from 25% to 60% and a larger dispersion. Conversely, the L-S index shows reasonable efficiency but lower precision for UPD, with no overlap O1 and dispersion values between 20% and 60%. For LS, CP and GC, its behavior mirrors the trend observed for the other indexes, with reliability decreasing at higher damage states due to greater overlap and scatter. After analyzing the behavior of the damage indexes in the BF and IF configurations, the most appropriate index for each building configuration can be identified. For BF configurations in all analyzed building types, most of the indexes effectively detect damage without misinterpreting the LS and CP/GC states, except for the FDR-Banon index. Among these indexes, Lybas and Sozen's index proves to be the optimal choice for all BF configurations, as it consistently has lower dispersion values for the CP and GC limit states. As far as IF configurations are concerned, the FDR-Banon index is the most efficient index for the pre-code moment-resisting frame. This index has the lowest overlap between the LS and CP/GC limit states and one of the lowest dispersion values for the CP and GC limit states. In contrast, Lybas and Sozen's index proves to be the most effective choice for both the moment-resisting frame and the shear wall system for code-compliant buildings. It minimizes overlap and dispersion while optimizing calculation time, making it the preferred index for these configurations. Although originally developed for structural RC elements, the evaluation of the efficiency and reliability of damage indexes in this study is extended to non-structural elements, such as masonry infills, which significantly affect repair costs after a seismic event. To achieve this, specific indexes are defined and tested to quantify the damage level of masonry infills. Among these, the index of Lybas and Sozen and the index of Powell and Allahabadi are selected as the most efficient and computationally effective options for calculating the damage level of masonry infills. In addition, a new dissipated energy-based index is introduced, based on the ratio between the area under the trilinear curve of the infill panel up to the point reached during the analysis and the total area under the trilinear curve. The effectiveness and adaptability of the analyzed infill indexes are evaluated by comparing the median values that each index assumes in each infill during the analyzed intensity measures (IMs) in the Multiple Stripe Analysis. Three threshold values are determined, corresponding respectively to the elastic limit of the infill, the maximum capacity of the infill and the failure of the infill. These three thresholds define four states of damage for the infill: the elastic and uncracked phase, the cracked phase, the softening phase and, finally, failure. These are shown respectively with green, yellow, light red and dark red color codes. The stage of each infill is defined based on the median value that each index assumes for the infill under investigation during the analyzed strip. The results showed that all three indexes were able to capture the growth and increase of infill damage in all building configurations studied, making these indexes an effective tool for detecting damage to closure panels regardless of building typology. In particular, the P-Al index and the energy-based index are particularly effective in progressively assessing damage to these elements.