The behavior of solid brick masonry is presented under the application of lateral loads. Two frames made of reinforced concrete, bare frame and masonry infilled frame, were subjected to displacement controlled lateral loading. Experimental tests and numerical modeling were performed, and the results compared show a good relationship. The analysis results match very well with the experimental observations. For numerical modeling of the infill wall, a modified micro-modelling approach is selected where the head and bed joints are lumped into the bricks and an interface model was defined between these bricks representing the behavior of the mortar joint. Appropriate material models and damage criteria are employed for each mode of failure. A parametric study was then performed to assess the influence of different material properties on the lateral load capacity of the RC frame infilled with masonry. It was demonstrated that for the same gravity load level the enhancement of brick unit properties enhances the total capacity of the RC frame with infill. Similarly, by increasing the gravity load on the structure with the same brick unit properties, the lateral load capacity increases considerably.