Comparison of seismic performance of knee braced steel frame and eccentric braced steel frame

Buildings under the action of the strong earthquakes undergo large displacements and may suffer significant structural damage, and even be destroyed catastrophically. Therefore, the structure should have enough rigidity and ductility to prevent excessive damage in the structural members. This can be accomplished by placing to the structure elements to be able to enhance earthquake resistance of the structure, such as a shear walls or steel braces, or dumpers. For this structure the knee braced frame (KBFs) and the eccentric braced frame (EBF) are commonly used structural elements to increase the earthquake resistance capacity of a structure in the seismic region. Therefore, the main aim of this thesis is to assess the seismic behavior of various eccentric braced steel frame and knee braced steel frame using nonlinear static analyses performed by SAP2000. This is achieved by focusing on a nonlinear astatic analysis, known as "pushover" analyses, to determine the seismic performance point of a 5-story steel frame building modeled with both eccentric braced frames and knee braced frames. As a result of several analyses, it was found that the shear capacity of the knee braced frame is higher than that of eccentric braced frame. In terms of the energy dissipating system, the energy dissipating capacity of KBF is better than EBF. Finally, it is concluded that since KBF combines excellent ductility and lateral stiffness, it can be one of the most effective lateral load bearing systems against seismic loads and is easy for application in the rehabilitation of earthquake induced damage to buildings.