This work summarizes the main aspects of the Guidelines for the Seismic Design and Verification of Masonry Infill Walls in Reinforced Concrete (RC) Buildings. Although primarily focused on RC structures, some principles may cautiously extend to infills in steel frames. The first version of the Guidelines originates from research promoted by the masonry industry (Morandi et al., 2017) and are largely based on studies conducted under the DPC-Reluis project, which has investigated the seismic behaviour of masonry infills since 2010. Eight research institutions (UNIPV, EUCENTRE, UNINA, UNIBS, UNIPD, UNIPA, POLITO, UNIROMA) 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 3.0-4.0 meters. 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 (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. The application of these Guidelines is expected to enhance the control of both in-plane and out-of-plane damage to masonry panels under seismic loading across multiple limit states. The document is subject to future revisions and updates, incorporating advances in research and code developments, including ongoing work from the Reluis 2024–2026 project (WP10–Task 10.3).