<p>The novel goal of this study is to investigate shear wall dimensions and arrangement on the seismic behavior of a reinforced concrete structure. To achieve the goal, an eight story concrete structure was modeled using nonlinear finite element software. Nonlinear time history dynamic analysis according to 2800 code used. Northridge acceleration was applied on the structure. Usual dead load and live load were also applied on the stories surface. Shear walls with 3 meters and 5 meters length were placed in four different arrangement, therefore totally eight models have been created. Maximum displacement of structure and absorbed base shear by walls will be discussed. Results generally showed that when shear wall length increases, absorbed base shear by shear wall and maximum displacement of the highest story increase too.</p>