Current World Environment

Today, a large number of residential and commercial buildings in the urban areas include one or several basement floors. The structural system and architecture of the basement floors are generally different, in a way that leads to a significant increase in the stiffness of the basement lateral load resistant system. to understand the impact of this change of stiffness on the seismic behavior of the structures, the two-dimensional concrete rigid frames with 4 and 8 stories and 3 openings are investigated. The performance of these frames was investigated both for no basement and 1, 2 and 3 basement floors conditions. In this study, SAP2000 is used for linear analysis of the models. In order to analyze the response history, 7 ground motions scaled based on static base shear of a frame with no basement were used. For modeling the change in concrete shear of the basement, a concrete shear wall was used. The results of the spectral analysis and response history analysis of this analytical study, was compared to the distribution of earthquakes in Earthquake loading height regulations. The effect of underground story presence on the seismic load distribution in a 4 story frame is more significant. With increasing the number of frame stories (above the basement) the presence of basement stories will have less impact on the distribution of shears in the frame stories.