PSI - Issue 78

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

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on studies conducted under the DPC-Reluis project, which has investigated the seismic behaviour of masonry infills since 2010. Eight research institutions (University of Pavia, EUCENTRE, University Federico II of Naples, University of Brescia, Univrsity of Padova, University of Palermo, Polytechnic of Turin, Univeristy “La Sapienza” of Rome) contributed to the development, with several also involved in revising Eurocode 8 Part 1-2 as part of the second generation Eurocodes. Targeted at both practitioners and researchers, the Guidelines focus on masonry infills that interact with the surrounding structural frame and are applicable to “ordinary” buildings with typical story heights of approximately 2.50 to 3.50 m. Tall infills, such as those used in industrial facilities, are excluded from the document’s scope. The design criteria and construction detailing recommendations are intended to complement existing codes, including Eurocodes and Italy’s national construction standards (DM 2018, NTC2018 and its 2019 Commentary). The Guidelines distinguish among different infill typologies, non-ductile, reinforced, and ductile (e.g., those with sliding or deformable joints that subdivide the wall into sub-panels), and provide related construction and classification criteria. The proposed design approach includes both simplified and explicit modelling of infills, in linear and nonlinear analyses, along with displacement-based verifications for in-plane behaviour. Particular attention is given to local effects on RC elements, especially columns, as well as to procedures for evaluating out-of-plane actions and resistance, accounting for in-plane/out-of-plane interaction. Global structural irregularities induced by infills, both in plan and elevation, are also considered, supporting the implementation of performance-based seismic design and assessment in line with current national and European regulations. Only a selection of the above-mentioned topics addressed in the document is briefly presented in the following sections. Applying these Guidelines is expected to enhance control and limit the in-plane and out-of-plane damage to masonry panels during seismic actions, while also mitigating the potential detrimental effects of infills on the overall structural performance. 2. Table of Contents and Masonry Infill Typologies The document is organized in seven chapters and two appendixes, as reported in Fig. 1. This document addresses exclusively masonry infills that interact with the surrounding structural frame, without specific separation joints between the structure and the masonry. Newly constructed infill walls must be realized after the concrete elements have sufficiently cured, or after the steel frames have been assembled. The infills should be realized in complete contact with the confining structural elements, as reported in Fig. 2(a). In accordance with the latest draft of Eurocode 8 - Part 1-2 (prEC8, CEN 2025), interacting infill have been classified into: • “Non-ductile/low-ductility” infills, which are unreinforced masonry (URM) walls without specific structural connections (i.e., without ties, shear connectors, or other devices). The infill masonry typologies reported in the Guidelines are with clay, concrete, AAC units. Based on the seismic performance of infill panels, particularly with respect to the interaction between in-plane and out-of-plane responses, clay masonry infills have been classified into the following categories, in line with the classification proposed in the latest draft of EC8-1-2: infill walls made with clay units of group 1, 2, and 3 according to the EC6-Part 1-1 (EC6, CEN 2022), with a thickn ess ≥20 cm and a compressive strength f k ≥ 3.0 MPa; infill walls made with clay units of group 1, 2, and 3 according to the EC6, without the above limitations; infill walls made with clay units of group 4 according to EC6. Examples of non-ductile infills are reported in Fig. 2(a). • “Reinforced” or “strengthened” infills, which are masonry walls with embedded vertical and/or horizontal reinforcement (in newly constructed or replacement infill panels), or with reinforcement meshes made of steel or composite fibers (e.g., glass fiber, aramid, etc.) embedded in specific plasters. Examples of reinforced infills are reported in Fig. 2(b). • “Ductile” infills, which are URM walls equipped with horizontal or vertical sliding or deformable joints that divide the wall into smaller sub-panels. They can generally sustain values of drifts much larger than non-ductile panels (see Table 1 in Section 4), without significant damage to the masonry, provide enhanced dissipation capacity, and significant out-of-plane stability. Ductile infills have been developed in several studies (e.g., Preti et al. 2012; Morandi et al. 2018; Verlato et al. 2016) and some examples are reported in Fig. 2(c).