One of the most common types of construction in our area, but also in the whole world, are reinforced concrete systems with unreinforced filled walls, with or without openings in them. Architectural formation of the building is defined by its masonry infill and it most often contains openings for doors or windows. The filled walls are considered as a non-constructive element which carries its own weight and it is implied that during seismic action the first to fail are non-constructive elements, while the reinforced concrete frames take on the impact of other constructive elements, especially seismic action and must secure global load, stability and safety of the whole construction. Building of masonry infill is oftenly not done by the rules of the profession and only the filled walls are built adjacent to the constructive reinforced concrete frame system and are connected to it. That leads to the conclusion that the load of a reinforced concrete frame system with filled walls can be observed as a unique constructive unit even though the influence of the infill on the load of the construction is most often ignored. Filled walls are most often modeled by using a diagonal pressure rod. The thickness of the rod during calculations is equal to the thickness of the wall while the width of the rod is determined, and that width of the rod gives engineers the biggest challenge as there are several approaches to determine the width of the rod, but the most appropriate approache is still being determined. This thesis shows a micromodel calculation made by using the method of finite elements in Atena 2D Engineering CAD software. Nonlinear calculation implies modeling of nonlinear behaviour of the materials, i.e. elements. Because the micromodel calculations are very demanding when modeling materials, they require careful entry of input data so the results of the calculation would be as accurate as possible in regards to the results of the actual experiment. As part of this thesis the behaviour and shear resistance of the constructive system frame - walls with bounded displaced opening for window under load of seismic activity in own plane was investigated. To determine the shear resistance of the system frame – walls with bounded opening for windows, a nonlinear micromodel calculation will be made in Atena 2D Engineering CAD software. Results from the micromodel calculation will be compared with results of the actual experiment.