rehabilitation of steel structures by using the rotational friction dampers

the rotational friction dampers can be improved the seismic behavior of the steel structures, and they can be reduced the internal forces in the bracing members, columns and the other structural members. in this research, a simple method for modeling and analysis of braced frames equipped by these dampers is proposed. the proposed model describes seismic behavior of dampers very well and it is applicable to analysis of braced frames with common sections in iran. braced steel frames with dampers and without dampers are considered for time-history dynamic analysis, and some parameters such as: base shear, axial forces of the columns and the bracing, drift of stories etc. for two different cases are compared. in the entire analyzes, the structure with damper has been shown the better performance and the more suitable seismic behavior than the structure without damper. then, use of frictional dampers for rehabilitation of existing buildings or designing of new structures with minimum weight is very useful.