PSI - Issue 78

Paolo Morandi et al. / Procedia Structural Integrity 78 (2026) 1293–1301

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Strength criteria addressing both vertical and horizontal bending, specifically for infill walls behaving as four-edge restrained plates, have been proposed, such as the method developed by Di Domenico et al. (2019). Additional approaches tailored for non-ductile infills are available in the literature, including those by Liberatore et al. (2020), Di Trapani et al. (2022), and Milanesi et al. (2022). The Guidelines also incorporate criteria for assessing reinforced infills, based on the studies by Morandi et al. (2013) and Minotto et al. (2020), which account for in-plane interaction effects. Finally, criteria for evaluating the out-of-plane resistance of ductile infills are provided for both sliding joint systems (Milanesi et al. 2020) and deformable joint systems (Verlato et al. 2016).

(a) (b) Fig. 6: (a) Vertical arch model with perfect bond to the frame; (b) reduction factor β R as a function of the inf-plane drift.

7. Conclusions This paper presents a summary of key contents from the forthcoming Guidelines for the Seismic Design and Verification of Masonry Infill Walls in Reinforced Concrete Buildings (Morandi et al. 2025a), developed through extensive research promoted by the DPC-Reluis project and the masonry industry. The Guidelines address the seismic performance of infills interacting with the surrounding structural frame and propose a comprehensive design framework, including classification of infill typologies, construction detailing, modelling strategies, and in-plane and out-of-plane verifications. Particular focus is placed on local effects on RC members and infill-induced global irregularities. By adopting the proposed recommendations, practitioners are expected to enhance control and limit the in-plane and out-of-plane damage in masonry panels with seismic action and mitigate the negative impact of infills on overall structural performance. The Guidelines are intended to complement current Italian and European standards, contributing to safer building design. The document remains open to future revisions and updates, which will reflect ongoing research advancements and developments in seismic design codes, including contributions from the Reluis 2024–2026 project (WP10–Task 10.3). Acknowledgements This research was supported by the Executive Projects DPC-RELUIS WP10 (2019–2021, 2022–2024, 2024–2026), as well as by previous DPC-RELUIS Executive Projects on the seismic response of masonry infills carried out since 2010. The financial support of the Italian Department of Civil Protection is gratefully acknowledged. References CEN, 2004a. Eurocode 8 - Design of structures for earthquake resistance, Part 1: General rules, seismic actions and rules for buildings, EN 1998 1, European Committee for Standardisation, Brussels, Belgium. CEN, 2022. Eurocode 6 - Design of masonry structures - Part 1-1: General rules for reinforced and unreinforced masonry structures, EN 1996-1-1. European Committee for Standardisation, Brussels, Belgium. CEN, 2025. Eurocode 8 - Design of structures for earthquake resistance, Part 1-2: Buildings, prEN1998-1-2_ Version of FprEN 1998-1-2:2025 (21/03/2025), as submitted to TC 250 for preparation of the Formal Vote in October 2025. European Committee for Standardisation, Brussels, Belgium.