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Recent seismic events that hit the central part of Italy have highlighted again the high vulnerability of the historical and architectonical heritage of Italy and the importance of preserving it. However, the seismic assessment of monumental buildings is particularly complex because each historical construction is a singular case realized by specific techniques. Therefore, the first step should be the knowledge of the building even if it is a difficult task. In the present paper, the seismic behavior of an important nineteenth century astronomical observatory, constructed between 1816 and 1819, was investigated. The building, located in Naples, in the southern part of Italy, and classified by the Italian code as an area of medium seismic hazard, was analyzed in the elastic and inelastic range under seismic actions. In this study, the results of two different models were proposed and critically compared. The first one was implemented by shell elements for walls and vaults developing a linear dynamic analysis, while the second one simulates the building through “equivalent frames” applying a nonlinear static analysis.

Summary Reinforced concrete (RC) frame buildings containing unreinforced masonry infill walls are commonly used in structural systems around the world. The performance of this type of building can be significantly affected by the presence of infill walls according to their type and distribution in the plane and along the height as revealed by earthquakes. This paper presents data collection, system identification, and finite element modeling of an existing RC framed building designed for gravity loads and containing unreinforced masonry infill walls. Based on a previously carried out ambient vibration test, a three‐dimensional finite element model, comprising infill walls and partitions, was successfully updated on the basis of the global modes identified by the in situ test, pointing out the important role of the nonstructural components for this type of building. The influence of the infill walls and partitions on the vibration period was examined, introducing a comparison with simple formulations for the period calculation suggested by codes or available in the literature. The updated model has been further used to assess an approach for an approximate estimation of the story and global stiffness of the building considering the effect of the secondary elements. The dynamic test with the model updating results an efficient procedure for a complete identification of the elastic behavior of the structure.

Masonry infill walls are commonly used in the frames of reinforced concrete (RC) buildings around the world. The seismic performance of these buildings is strongly affected by the presence of the infill walls and partitions, as shown by the post-earthquake damage in many cases. The effect of these components is particularly important for RC frame constructions underdesigned for seismic actions that usually are characterized by deformable frames magnifying the contribution of the infill walls to the seismic response. Also the flexibility of the floors could be influenced by the collaboration of the infill walls to the transversal stiffness of the building. The paper addresses the seismic assessment of a typical infilled RC frame building designed only for gravity loads in the 1960s in the Southern of Italy that currently is a high-seismic zone. The structural identification of the building based on ambient vibration test has been already done pointing out the significant role of infill walls and partitions through the updating of the numerical model. Based on the results of the calibrated model, the effect of the floor flexibility on the dynamic behavior of the structure is discussed, and the seismic capacity at life safety limit state (LSLS) is assessed by means of the linear dynamic analyses. The effects of the infill walls on the seismic performance of the building are discussed in detail considering a strengthening solution that involves the infill panels as masonry walls cut from the RC columns to avoid the local interaction but strengthened by composite grids in mortar matrix (FRCM).

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