PSI - Issue 44

P. Sorrentino et al. / Procedia Structural Integrity 44 (2023) 1648–1655 P. Sorrentino et al./ Structural Integrity Procedia 00 (2022) 000 – 000

1649

2

1. Introduction In recent years, the ancientness of Italian building heritage and the several damages and collapses caused by violent earthquakes have led to a substantial increase in attention on the issue of seismic vulnerability assessment. For unreinforced masonry structure (URM) this evaluation is a complex task as in many cases they are not isolated structure but aggregated. Especially in Italian historical centres, historical building aggregated are the result of the progressive growth of towns, in which elevation floors are added to existing buildings and plan enlargements are made by adding structural portion to existing ones (Formisano et al., 2010). This is the case of Zoological Station Anton Dohrn in Naples, a complex masonry building that includes six parts (the central part, West wing, East wing, two connecting parts and the library) built in different periods. The topic of seismic assessment of structures has often been studied by the authors (Velente et al., 2020; Brandonisio and De Luca, 2021; Brandonisio et al, 2020). In this paper the seismic vulnerability of the structure has been evaluated via nonlinear static analysis and some preliminary considerations on geometric parameters, as the ratio between the area of masonry walls and the geometric area have been done. By discussing the results obtained, a proposal for the evaluation of seismic vulnerability of complex masonry buildings with additions of structural portion is formulated. 2. Case study: Zoological Station Anton Dohrn in Naples The Zoological Station Anton Dohrn in Naples is a complex masonry building located in Villa Comunale, in the neighbourhood of Chiaia. It is the result of six parts (the central part, West wing, East wing, two connecting parts and the library) built in different periods (Figure 1). The central part of structure was built between 1872 and 1875 and is the first part of the complex building. The other parts were added to it in the years listed below: • West wing, in 1880; • the two connecting parts and the East wing, in the early 1900s; • the part hosting the library, which connects the central part to the West Wing, in the 1950s. The central part and the connecting parts have been analysed in the following sections.

Figure 1. Planimetry.

2.1. Description In this section the descriptions of the central part and the connecting parts are given.

The central part of Zoological Station is a masonry building characterized by rectangular plan of dimensions 32x22m (Figure 2b). As it can be observed from the sections in Figures 2a and 2c, it consists in four levels and an underground one, with an overall height of 19m. The underground floor, the ground floor, the first, the second and the third floor are characterized by an understorey of 2.60, 5.5m, 4.30m, 3.40m and 3.10m, respectively. The thickness of the main walls varies from 160cm at the underground floor, to 40cm at the third floor. The structure is made of brick and tuff masonry with the presence of superfetation in steel and r.c.. In Table 1 the mechanical properties of masonry are listed. The floors consist of different typologies of vaults and roof with steel beams.