PSI - Issue 78

Fabio Micozzi et al. / Procedia Structural Integrity 78 (2026) 1205–1212

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3. Behavior analysis of structure affected by surface faulting In this chapter, five different cases of structure crossed by the surface faulting will be described. For each of them a brief description is provided and the reason of the behavior observed is given. The case shown in Fig. 5, also reported by Aydan et al. (2024), is a two-storey reinforced concrete house with a shallow foundation (POI_3, see Fig. 3). The fault trace passed just underneath the building. The fault horizontal displacement measured on a walkway by the authors at 70 m distance was ca. 1 m, while in Aydan et al. (2024) is reported a fault displacement of more than 2 m. The building did not suffer any significant damage except for part of the perimeter external walls, reconstructed at the time of the renaissance. The rigid displacement of the building due to the faulting strike was clearly visible from the gap of more than 30cm between the building and surrounding walls. This example clarifies how a raft foundation of a compact and short building can easily survive the fault strike “floating” on the surface.

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(b)

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Fig. 5. (a) reinforced concrete building with no damage; (b) gap due to the rigid rotation of the building; (c) fault displacement (POI_3, 36.486057, 36.338732, 0 km from the fault, 1m measured horizontal offset at 70 m distance)

The second case shown in Fig. 6 (POI_4, see Fig. 3) is the Tuba Plaza (see also Damc  et al. (2025)), a 9 floor building composed by two separated adjacent structures, with almost no seismic gap between them (in Fig. 6c). Also in this case the fault passed exactly under the building, with a strike estimated around 1 m, measured by the authors at 1.5 km distance and estimated also on the site by the wall displacement observed on the right side of the building Fig. 6d. After the earthquake, the two blocks rotated resulting in around 1m displacement of the front façade, as shown in Fig. 6. As expected, the block on the right, the one intersected by the fault, rotated counterclockwise, leaning against the structure on the left at the rear side and opening a gap at the front façade of about 1 m (Fig. 6a). The are no available information regarding the foundation typology. However, also in this case the compactness of the structure made possible to sustain the rigid rotation without significant structural damage (Fig. 6b). The third case, reported in Fig. 7 (POI_5, see Fig. 3), is a two-floor reinforced concrete building of a school. The fault passed on the back right edge of the structure, intersecting an annex (Fig. 7b) attached to the principal structure . The shallow foundation of the main building resisted perfectly to the fault displacement while the annex has nearly subsided. In this case, it is possible to observe how the surface fault trace deviated from its expected straight path, appearing to circumvent the main structure foundation (Fig. 7c and d). This suggests that the fault rupture, upon reaching the surface through soft soils, may have been influenced by the presence of the building's foundations. The foundations likely caused a local increase in ground stiffness and strength. As a result, the rupture path was deflected around the structure rather than propagating directly under it. This concept is important when considering the capability to follow the surface rupture in a dense built environment context.