Today, the seismic resistance of existing structures and structures has become one of the most important issues in earthquake engineering. Often, buildings requiring earthquake resistance are divided into two main groups: the first group of buildings that were designed and constructed prior to the development of any seismic criteria or after their construction, but which have not been complied with and are now exploited. It continues. Such buildings are, in most cases, designed for gravity loads and lack any seismic stability, especially against strong and severe earth movements. In the second group, buildings that are designed and implemented in accordance with certain seismic conditions are now required to be modified due to changes in these criteria and possibly the increase in the level of design forces or changes in the formulation requirements. In our country, due to various reasons, and especially due to the economic aspects of the problem, the focus is on rehabilitating the first group buildings. In this paper, first, to determine the best earthquake mapping acceleration for using the time history analysis method, then a seismic analysis is performed on the modern steel frame and the results are observed.