The contribution of infill masonry (IM) walls to the seismic performance of buildings can be favourable or not depending on several phenomena, detailing aspects and mechanical properties such as the relative stiffness and strength between the frames and the masonry walls, the type of connection between masonry and surrounding elements, etc. From survey on damaged and collapsed reinforced concrete (RC) buildings in recent earthquakes a large number of buildings that suffered severe damage or collapse had their poor performance associated with the influence of IM panels, wherein two main mechanisms have been reported. The IM out-of-plane behaviour has been observed as one of the most important critical failures of such type of non-structural elements. This research focuses on the development of a simplified macro-model to account for the out-of-plane behaviour of the IM, including the corresponding interaction between in-plane and out-of-plane, when subjected to seismic loading. That macro-model, implemented in the OpenSees software framework, is an improvement of the commonly adopted equivalent bi-diagonal-strut model, in which the out-of-plane behaviour is considered through the implementation of the element removal algorithm. Additionally it was evaluated the seismic safety assessment of an 8 storey building considering the effect of the IM out-of-plane behaviour in the structural response.