Seismic behavior of connection with surrounded stiffeners in the proposed moment frames

To ensure the rigidity of the connection in the moment frame system, continuity plates are used at the level of the beam flanges. In box columns, due to the closed section, it is difficult to implement and is not very reliable. The present study introduces a new connection with external stiffeners. In the proposed connection, trapezoidal external stiffeners are used at the level of the beam flanges so that while transferring the force safely from the beam to the column, it can meet the seismic criteria of the connection well. The mentioned connection was investigated in two cases, first; hollow steel section and second column filled with concrete, and the sensitivity analysis of the thickness of the stiffeners were performed. ANSYS software was used to achieve the research objectives. SHELL element is used in modeling steel sections and SOLID element is used for modeling concrete. The parameters studied in the present study to express the adequacy of the connection are: strength, fixed percentage, connection cycle behavior, ductility, energy absorption and stress distribution across the connection. The results of studies show that the introduced connection provides the seismic criteria of the connection well and due to the increase in the width of the beam flange in the areas around the plastic hinge column, it leads to a safe and controlled area inside the beam.