<p>The shear behavior of rock joints is governed by the morphology and boundary conditions. However, most existing shear models cannot accurately capture the contributions of two-order asperities (waviness and unevenness) and non-stationary angles (i.e., the angle between the nominal plane and the shear direction, reflecting the uphill/downhill shear tendency). Here we propose a constitutive model incorporating the progressive degradation of three-dimensional asperities with explicit contribution of the non-stationary angle, based on the mobilized shear strength theory. The geometric parameters of two-order asperities are quantitatively separated, and the non-stationary angle is introduced into the constitutive relationship as a key joint property. By adopting a 3Dasperity degradation principle derived from the plastic tangential energy, an analytical shear model for rock joints is established. The proposed model is capable of modelling the entire shear process of joints. In the numerical implementation, the forward Euler method is employed for iterative solution, allowing simultaneous yielding of shear stress and dilation as a function of the shear displacement. Systematic laboratory direct shear tests were performed to investigate the mechanical responses of joints with distinct non-stationary angles under different normal stresses. The constitutive predictions agree well with the experimental results, demonstrating the validity and applicability of the proposed model. The involved parameters possess clear physical meanings and can be obtained from fundamental laboratory tests and 3D morphology. The proposed model may reliably represent the shear behavior of rough rock joints and evaluate pertinent rock-engineering stability.</p>