Unreinforced masonry (URM) buildings are often vulnerable to out-of-plane (OOP) collapse mechanisms due to vertical one-way bending triggered by the local activation of wall segments under seismic loading. The assessment of such mechanisms has been widely addressed in the literature, typically assuming rigid body behavior and employing single- or multi-degree-of-freedom (SDOF/MDOF) representations. In this study, the OOP response of masonry walls is investigated through an extensive parametric analysis, accounting for variations in wall geometry (height and thickness), vertical overburden, and the position of the wall along the building height (i.e., floor level). The interaction with the global in-plane response is represented through an equivalent SDOF model that captures the amplification of seismic demand along the height and enables the derivation of floor acceleration spectra. Numerical analyses are performed assuming vertical spanning strip walls undergoing one-way bending, modeled through a simplified SDOF system. Both nonlinear dynamic simulations and code-based nonlinear kinematic procedures are conducted and compared in terms of displacement demand. The results are discussed in the context of code-based assessment frameworks, highlighting the strengths and limitations of simplified approaches in reproducing the dynamic response of OOP mechanisms.