# Seismic Assessment and Strengthening of a Load-Bearing Masonry Structure Considering SSI Effects
## 6 Discussion  
The analyses conducted under both static and dynamic loading conditions reveal critical differences in the structural behavior of Models 1 and 2, and highlight the influence of soil-structure interaction (SSI) on their seismic performance. With regard to the static analysis, soil-structure interaction results in varying tensile stress distributions across the building elevations, thereby preventing the derivation of reliable conclusions. However, a comparison of compressive stresses within the building's external masonry indicates that models incorporating SSI effects exhibit lower stress levels. The two models, M1 and M2, were subjected to particularly high seismic loads. Elastic dynamic time history analysis of the selected events revealed significant damage across all four elevations of both models. This damage includes the ramming of the external masonry by floor joists and transverse masonry, and pertains to the influence of roof loads on the external walls, as well as to both in-plane and out-of-plane failure mechanisms. These mechanisms indicate potential wall collapse, as evidenced in the SMAX tables for Elevation 4. However, the observed failure pattern of the second floor does not accurately reflect its actual structural behavior, as the wooden elements were not simulated. Consequently, the influence of the embedded timber frames (friggia) and the timber-framed internal walls was not taken into account, rendering the second-floor masonry more vulnerable to seismic actions. Regarding SSI influence, the conclusions according to Tables 11 and 12 are summarized below:  
Ground floor:  
* In Model M1, the maximum SMAX value is observed in case M1 ssiKoc1, exhibiting a 93% increase compared to M1 fKoc1. Stress increases are observed across all M1 ssi models, ranging from 15% to 93%. * In Model M2, the maximum SMAX value is observed in case M2 ssiNor1, exhibiting a 55% increase compared to M2 fNor1. The Kah1 and Kah2 events exhibit stress reductions under SSI conditions. Overall, the observed increases range from 26% to 55%, while the reductions range from 13% to 19%. * A comparison between Models M1 and M2 reveals an increase in stress across all M2 cases, with the exception of M2 ssiKah1, which presents a 14.25% decrease relative to M1 ssiKah1. Additionally, all M2 cases exhibit a delay in the timing of peak stress occurrence compared to M1. 2 nd floor:
* In Model M1, the maximum SMAX value is observed in case M1 ssiKah1, exhibiting an increase of 123.24% compared to M1 fKah1. All cases show increases ranging from 78% to 125%, indicating that stress increases on the first floor are significantly higher than those on the ground floor. * In Model M2, the maximum SMAX value is observed in case M2 ssiNor2, exhibiting an increase of 32% compared to M2 fNor2. However, the greatest increase occurs in the Koc2 event, reaching 50%. Unlike the ground floor, no event exhibits stress reduction under SSI conditions. Overall, stress increases in this model range from 1% to 50%. * A comparison between Models M1 and M2 shows that all M2 fix models exhibit increased stress, except for cases M2 fkah1 and M2 fKoc2. In contrast, M2 ssi modelsshow a reduction in stress compared to M1 ssi. Finally, similar to the ground floor, all M2 cases--except for M2 fKoc1--exhibit a delay in the timing of peak stress occurrence compared to M1. The findings indicate that the influence of soil-structure interaction (SSI) on stress amplification is more significant in Model M1, which exhibits a shorter fundamental period due to increased stiffness resulting from masonry consolidation via grout injection. Model M2, by comparison, which features greater mass, reduced masonry stiffness, and a longer fundamental period than M1, also experiences stress increases under SSI (with the exception of the Kahramanmaras earthquake), albeit to a lesser extent. It is also important to note that, on the second floor, soil-structure interaction results in stress reduction across all combinations for Model M2.