Finite Element Model of a Three Story Steel Frame with Bolted Connections and End Plates

Due to uncertainties manufacture of flange connections and complexity of their semi-rigid behavior, the behavior of such joints in the structure and the behavior of them when they are studied separately is different. In the present study, the behavior of a flanged joint system in real condition in a three story steel frame, three dimensional inverse problem solving method has been determined. To simulate the behavior of such a joint (beam elements and two plates with small gap from each other), a three story steel frame was modeled using finite element method. Frequencies vibration modes of structure for different modulus of elasticities were obtained using modal analysis. For the updating process for the three story steel frame, three dimensional finite element model by reducing the differences between experimental and analytical natural frequencies, the element beam flange connection system was replaced with specified Young’s modulus. Updated model, while providing a good approximation of natural frequencies in three story steel frame, a flexible behavior in different degrees of freedom could be attained to demonstrate the semi-rigid behavior in the structure.