PSI - Issue 78

Adriano Andrés Del Fiol et al. / Procedia Structural Integrity 78 (2026) 1713–1720

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1. Introduction The Italian territory is fully characterized by reinforced concrete (RC) frame buildings infilled with masonry walls. is usually neglected Although different studies and experiences in earthquake-prone regions have shown that masonry infill can bring to unexpected brittle failure mechanisms, the influence of non-structural elements. Several state-of the-art studies investigated the interaction between the stiff masonry infill and RC frames, like Negro et al. (1997), Cosenza et al. (2000), Papia et al. (2003), Dizhur et al. (2016), Blasi et al. (2018a), Blasi et al. (2018b), De Risi et al. (2018). For this reason, the most recent national and international building codes, e.g., Norme tecniche per le costruzioni (2018) and CEN (2015), recommended to consider the infill contribution to the RC frame response, especially in the case in which the masonry walls are not appropriately separated from the bare frame. The most recent practices consist of adopting dry construction techniques for infill panels, in order to reduce weight, construction time and improve sustainability of constructions. Among available techniques, cross laminated timber (CLT) panels offer considerable sustainability benefits due to a reduced carbon footprint and a natural capacity to retain carbon absorbed during tree growth. At the same time, the use of lightweight materials mitigates seismic forces, while the prefabrication processes facilitate rapid construction. Furthermore, CLT infills generally enhance the lateral response of RC frames (Stazi et al. 2019), Li Cavoli et al. 2023), offering higher stiffness, strength, and energy dissipation if compared to masonry. As shown by the recent literature, CLT infills might be used not only for new constructions but also as retrofitting technique in existing structures, see for example Smiroldo et al. (2021), Smiroldo et al. (2023a), Smiroldo et al. (2023b), Smiroldo et al. (2023c). Still, the performance of CLT infills is strongly influenced by the connection solution, as highlighted by Gavric et al. (2015), Smiroldo et al. (2020), Aloisio et al. (2021), Tuhkanen et al. (2021). The study herein presented is part of an experimental project aiming to assess the advantages of CLT panels in terms of structural and seismic performance. The experimental campaign investigates different infill panels, accounting for masonry and CLT, characterized by different openings configurations, in order to assess the in-plane structural response of infilled frames under seismic loadings. This paper presents the first numerical outcomes for a benchmark case-study available in literature (Calvi and Bolognini, 2001), with the aim of calibrating a numerical modelling approach at the base of further investigations. The study replicates the experimental setup, including geometry, materials, and loading protocols, in the finite element (FE) software ABAQUS (2024). The results of the investigation show a near-good agreement between experimental and numerical results, revealing the proposed approach as adequate for investigating the seismic performance of innovative infill solutions like CLT. 2. Reference Experimental Framework The preliminary investigation was performed on the experimental test by Calvi and Bolognini (2001), which examined the seismic response of RC frames when infilled with masonry panels. The experimental model consisted of a full scale, single-bay, single-story frame with an interstory height of 3.0 m and a bay width of 4.2 m. The RC frame, reported in Figure 1,) was designed in accordance with Eurocode 2 provisions (CEN, 2015). The structural design was executed in accordance with capacity design principles, using a high ductility class. The configuration that was selected for model calibration corresponds to the unreinforced masonry infill condition that was tested in that particular campaign. The infill panel measured 4200×2750×135mm, combining a 115mm-thick clay block wall with 10mm of plaster on both faces. The masonry units were composed of highly perforated hollow clay blocks (245 mm × 115 mm × 245 mm), which were laid with horizontal holes. This configuration resulted in equivalent stiffness in both the vertical and horizontal directions. The material properties of the masonry were as follows: an average compressive strength of 1.11MPa (parallel to the holes) and an elastic modulus of approximately 991MPa. The in-plane testing protocol applied three fully reversed, displacement-controlled cycles at each drift level. Drift amplitudes of 0.1%, 0.2%, 0.3%, and 0.4% were utilised to evaluate serviceability and low-damage states, whereas 1.2% and 3.6% represented heavy damage and near-collapse conditions, respectively.