Floor Response Spectra for the Verification of Secondary Elements in Masonry Buildings

A critical issue in the seismic assessment of existing buildings is the accurate definition of the filtered seismic input to verify secondary elements (SEs) such as pinnacles, parapets, or artistic pieces. SEs are highly vulnerable, and their potential collapse represents significant cultural, economic, and safety risks. The seismic demand on SEs is influenced by the dynamic characteristics and damping properties of both the building and its SEs. This filtering effect leads to floor accelerations that differ considerably from ground accelerations. Current codes recommend assessing the filtered seismic input using floor response spectra (FRS), which can be estimated through various formulas available in the literature and technical codes. These formulas are essential for the seismic protection of monumental buildings, as they must accurately assess amplification phenomena and account for nonlinear effects due to structural damage. While experimental tests and numerical simulations offer valuable insights, real-world data from earthquake-affected structures are crucial to validate models. In this context, this paper presents the application of available analytical expressions to predict FRS at increasing floors in four unreinforced masonry buildings monitored by the Italian Seismic Monitoring Network. To verify the consistency of the selected expressions, the analytical FRS are compared with those derived from recorded floor accelerations.