# Seismic Assessment and Strengthening of a Load-Bearing Masonry Structure Considering SSI Effects
## 1 Introduction
The response spectra of the selected ground motions were scaled to match the EC8 design spectrum within the period range of 0.2 T to 2 T, where T is the fundamental period of the system in each seismic direction. Additionally, in order to compare the original and the existing structural systems, two finite element models were developed, one excluding and one incorporating RC elements. It should be noted that interventions involving reinforced concrete (e.g., slabs and bond beams) can have a significant impact on load-bearing masonry buildings, depending on factors such as the adequacy of slab-to-masonry connections, the proper use of reinforcement [4], and whether the intervention is accompanied by masonry strengthening [2]. Finally, given that the building is founded on class D soft soil, as defined by EC8, soil-structure interaction (SSI) effects were also investigated for each model. The results of the analyses are compared with those of the study by [PERSON] et al., 2023 [16] which analyzed the seismic behavior of a historic building under both fixed-base conditions and soil-structure interaction (massed and massless) across three different soil categories: hard, medium, and soft. The results are also compared with the study of [17]. Also, [PERSON] [18] examined the impact of soil-structure interaction (SSI) effects on the seismic analysis of cultural heritage buildings, such as the Mosque-Cathedral of Cordoba in Spain. An investigation of [PERSON] [19] was conducted into the variations in the seismic response of a historical masonry church, utilizing four different SSI models in addition to a fixed base model that did not consider SSI. Furthermore, the research of [PERSON] and [PERSON] [20] examines the seismic response of the historical Lala Mehmet Pasha minaret by taking into account Soil Structure Interaction (SSI). The influence of SSI on the out-of-plane performance of an ancient structure in Iran, known as Arge-Tabriz has been investigated by [PERSON] et al., [21]. [PERSON] et al., [22] explored the seismic performance of St. Titus Church located in Heraklion, Crete, Greece, along with the necessity for its seismic retrofitting. Additionally, the impacts of soil-structure interaction have been considered. This research tackles significant deficiencies in the seismic evaluation of historic masonry structures by offering a thorough analysis that concurrently takes into account original construction methods, contemporary strengthening measures, and the effects of soil-structure interaction, elements that are seldom analyzed together in the current literature. The engineering significance of these structures is underscored by their dual function as cultural heritage assets and operational public buildings, rendering their seismic safety crucial for both the protection of lives and the preservation of heritage. Historic load-bearing masonry edifices, such as the Archaeological Museum of Lemnos, are especially susceptible due to their age, material deterioration, and construction techniques that predate modern seismic regulations. Nevertheless, they must continue to fulfill modern roles while preserving their historical authenticity. The originality of this study arises from its direct comparison of two strengthening approaches, traditional grout injection against modern reinforced concrete solutions, utilizing the same analytical methods and realistic seismic inputs that adhere to Eurocode 8 standards [23]. By integrating soil-structure interaction effects for Category D soils and concentrating on quantitative metrics like interstorey drift ratios and peak tensile stress, this research offers valuable insights for engineers and conservators striving to reconcile structural safety with heritage preservation needs, while also establishing a replicable framework for evaluating similar composite timber-framed stone masonry systems globally.