Numerical models are usually adopted when approaching the analysis of masonry structures due to the advantages in addressing the material non-linearity and its quasi-brittle response. Throughout the years, several approaches have been developed, tackling the problem from different perspectives. One of them relies on the use of Block-based models (BBMs) which allow to explicitly consider the micro-mechanical features of masonry, offering a high-fidelity model of the material response. This can be further idealized by adopting continuum models (CMs), which represent masonry as an equivalent homogeneous material overlooking the blocks-joints arrangement. However, the computational cost of BBMs is generally high, and CMs are still preferred for the analysis of large-scale structures, provided that a proper constitutive framework is employed. For such aim, mechanism-based damage models have been recently proved to be promising in accurately describing the non-linear material behaviour, e.g. in the case of composite materials [1]. In this contribution, a continuum damage model for the analysis of in-plane loaded masonry structures is proposed. The mechanism-based strength domain recently presented in [2] is employed to characterize the damage onset. Accordingly, the model is characterized by a set of damage variables describing different failure typologies, including failure in blocks, in the joints and mixed blocks-joint failure. The damaged constitutive tensor representing the material quasi-brittle response is then obtained under the assumption of strain-energy equivalence. The model is implemented in a finite element code and the potentialities of the approach are shown by considering simple structural examples, including a comparison with available reference experimental and numerical results. REFERENCES [1] Rivet, I., Dialami, N., Cervera, M., & Chiumenti, M. (2024). Mechanism-based damage and failure of fused filament fabrication components. Composites Part B: Engineering, 270, 111119. [2] Bertani, G., Patruno, L., D’Altri, A. M., Castellazzi, G., & de Miranda, S. (2024). A single-surface multi-failure strength domain for masonry. International Journal of Solids and Structures, 288, 112624.