<p>Rock bridges play a significant role in the stability of rock slopes, but their influence on shear strength parameters and failure patterns in design analyses is not well understood. In this study, the effect of the number of joints with an equal percentage of rock bridges (K) at different angles (β) on the shear behavior and failure pattern of andesite with planar non-persistent joints under different normal stress has been investigated using lattice spring-based synthetic rock mass (LS-SRM) modeling approach utilizing SRM tools. Initially, several LS-SRM models were developed and calibrated using data from experimental laboratory tests to ensure the simulated numerical models’ accuracy. Subsequently, numerical direct shear tests were simulated and the progression of failure was visually monitored. The findings from the simulations revealed that models containing pre-existing planar cracks demonstrated a combination of wing cracks, anti-wing cracks, shear cracks, and secondary cracks. Additionally, with the increase of the rock bridge angle, the failure pattern changes from tensile cracking to shear cracking. The cohesion increases by approximately 60% as the angle of the rock bridge changes from 90° to 135°, after which it stabilizes. In contrast, the friction angle remains unchanged. Moreover, an increase in the number of joints from one to two and then three results in a decrease of almost 4% and 10%, respectively, in the internal friction angle, while there is a negligible change in cohesion. The results demonstrate a nonlinear relationship between shear strength and varying rock bridge angles. Specifically, shear strength increases by approximately 50% from a bridge angle of 90°–135°, and by 5% from 135° to 180°. Furthermore, Normal stress has the greatest influence on shear strength, while the number of joints has the least impact.</p>