In-plane and out-of-plane seismic damage of masonry infills in existing r.c. structures: the case study of De Gasperi-Ba
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In‑plane and out‑of‑plane seismic damage of masonry infills in existing r.c. structures: the case study of De Gasperi‑Battaglia school in Norcia Fabio Mazza1 · Angelo Donnici1 Received: 10 June 2020 / Accepted: 10 October 2020 © The Author(s) 2020
Abstract A significant correlation between the in-plane (IP) and out-of-plane (OOP) damage propagation of masonry infills (MIs) is frequently observed after strong earthquakes, posing a serious problem as regards vulnerability of public buildings such as schools. The present work is aimed at identifying the effects of different IP and OOP modelling assumptions of MIs on their seismic damage. To this end, the state secondary school De Gasperi-Battaglia in Norcia (Italy), object of monitoring by the Department of Civil Protection since 2000, is investigated for the heterogeneity of infill typologies. The school is composed of a basement and three storeys above ground level, with a reinforced concrete (r.c.) framed structure having a long-shaped rectangular plan. Two typologies can be identified in terms of transverse layout of MIs: (i) double-leaf interior partitions, made of hollow clay bricks; (ii) double-leaf exterior infill walls, constituted by facade solid bricks paired with hollow clay bricks. In addition, partial height infills in the longitudinal direction, due to classroom windows, make the columns susceptible to short column effects. MIs are represented by a five-element macro-model predicting both in-plane (IP) and out-of-plane (OOP) behaviour through a horizontal nonlinear truss and four diagonal nonlinear beam elements, respectively. Stiffness and strength values in the OOP direction are also reduced considering the evolution of the IP damage. Three assumptions are investigated for the behaviour of structural MIs: i.e. elastic both IP and OOP; inelastic IP and elastic OOP; inelastic both IP and OOP. Bare and infilled test structures are subjected to biaxial spectrum-compatible accelerograms, to evaluate the IP and OOP damage levels and effectiveness of the OOP simplified verification proposed by seismic codes. Keywords R.c. framed buildings · In-plane nonlinear modelling of masonry infills · Outof-plane nonlinear modelling of masonry infills · Seismic analysis
* Fabio Mazza [email protected] Angelo Donnici [email protected] 1
Dipartimento di Ingegneria Civile, Università Della Calabria, 87036 Rende, Cosenza, Italy
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Vol.:(0123456789)
Bulletin of Earthquake Engineering
1 Introduction Simplified methods are generally used for the out-of-plane verification of masonry infills (MIs) placed at different floor levels of a building, specifying equivalent static design forces on the basis of floor response spectra of acceleration (e.g. NTC18 in Italy, Eurocode 8 in Europe and FEMA 356 in USA). However, recent ground motions (e.g. L’Aquila 2009) have highlighted that seismic codes may lead to erroneous safety estimations. Unreinforced MIs can be typically found in reinforced concrete (r.c.) framed buildings, but they are commonly neglected in
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