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The interaction between an infill panel and a reinforced concrete (RC) column can lead to the brittle failure of the structural element. A novel combination of cutting-edge analytical modelling approaches for masonry infills and RC elements is employed to simulate five experimental tests (three infilled and two bare) characterized by brittle failure modes. The infill is modelled with a multi-strut idealisation, and the RC column is modelled using the recently developed PinchingLimitStateMaterial in OpenSees. The effects of the infill type (solid or hollow) and ductility characteristics of the RC elements on the optimal modelling parameters are investigated. The focus of this study is on the assumption of the overstrength ratio between the maximum and cracking strengths of the panel when brittle failure occurs. The preliminary assumption for this parameter is the widely accepted value of 1.3 suggested in the formulation by Panagiotakos and Fardis. This value is found to influence the shear failure simulation. To more accurately predict brittle failure, higher overstrength values of the infill are used in the numerical model to improve the matching between the numerical and experimental tests. These values are then compared with the approximate estimation of the overstrength ratio from a database of 98 experimental tests. The suggested estimation of the overstrength ratio is systematically greater than 1.3 and dependent on the infill type (i.e., 1.44 for hollow and 1.55 for solid infills). The proposed values can have a high impact on future code-compliant recommendations aimed at verifying the likelihood of the occurrence of brittle failure in columns due to their interaction with infill panels. KEYWORDS: masonry infilled reinforced concrete frame; experimental tests; equivalent strut model; shear failure; infill overstrength. * Corresponding author Numerous studies were conducted on different types of infilled frames to provide simplified analytical models to evaluate the forces transferred to the frames, depending on the failure mode of the infill (e.g., Mehrabi et al. 1996;Colangelo 2005;Cavaleri and Di Trapani 2014;Noh et al. 2017). At the onset of damage in the panel, a strut mechanism occurs due to the migration of the stresses to the diagonal zone, and stresses at the interface between the corners of the panel and the frame members increase. Experimental studies on the local interaction between frames and masonry panels showed that, in the case of poor transverse reinforcement of the columns, early shear failure can occur due to the presence of the infill Basha and Kaushik 2016;Verderame et al. 2016). Based on the experimental observations, different analytical models were derived in the literature to consider the effect of the infill panel on the response of RC frames under lateral loads. Many numerical analyses aimed at simulating the local interaction phenomena through micro-and macro-modelling approaches (e.g., Stavridis and Shing 2010;Jeon et al. 2015;Ning et al. 2017). The equivalent truss macro-model...

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The research on infilled reinforced concrete frames is fundamental for the vulnerability assessment of existing buildings.The analysis of the interaction between infill and frame is an open issue in performance-based earthquake engineering, due to its importance in predicting the dynamic behaviour and failure modes of buildings. This study provides an open access database of laboratory tests on masonry infilled reinforced concrete frames, collected from the literature and harmonized in a consistent framework.The data were grouped in categories, to calibrate a piecewise linear curve representing the lateral response of the infill, depending on the masonry wall and the frame details. The gathered data are used to assess analytical models and numerical studies from the literature, with the aim to revise the formulations currently used in the equivalent strut approach. An empirical model for the equivalent strut was developed, through a power-law multiple regression of the database. The open access database in its spreadsheet form is aimed at providing a useful tool for the analysis of infilled reinforced concrete frames.