Understanding the mechanical behavior of masonry structures when subjected to extraordinary actions is still an active field of research due to the composite nature of the constituents. Various computational and analytical methods have been used to predict masonry structure behavior. In the context of the geometrical features of the model, the computational modeling strategies are divided into four categories: macro-element modeling, macro-modeling, simplified micro-modeling, and detailed micro-modeling. This study introduces a contact constitutive model under the simplified micro-modeling strategy, developed within a distinct element framework with an explicit time-marching integration scheme. This constitutive model is formulated according to the damaged plasticity concept similar to the one proposed by Pulatsu [1]. The difference lies in the user-defined piecewise linear softening function implemented to capture the softening regime in compression, tension, and shear. Additionally, the compressive region is limited by a compressive cap according to the formulation defined by Louren¸co and Rots [2]. A simple radial return algorithm is employed once the cap mode is violated, allowing an implicit coupling of the shear and compressive behavior of the joint interface. The proposed constitutive model enables the prediction of the post-peak strength degradation in all regions, allowing an accurate representation of cracking-shearing-crushing of the unreinforced masonry structures. The performance of the contact constitutive model is assessed from a series of unreinforced masonry wall experiments subjected to combined shear-compression. A comparison between the experimental and numerical results is drawn, resulting in a relatively accurate prediction of the global behavior through load-displacement responses and the local behavior in terms of the damage patterns.