The Research On Static Behavior Of Top And Seat Angle Semi-rigid Connections

In typical designs of steel frame structures, the beam-to-column connections have been idealized as fully rigid or pinned to simplify the calculation. However, it has definitely been shown by experimental results that all of the connections do behave nonlinearly between fully rigid and pinned, they belong to semi-rigid ones. In order to effectively design the frame work with semi-rigid connection, the characteristics of semi-rigid connections must be estimated and considered in structural analysis.In this paper, top and seat angle connections are analyzed to obtain mechanical behavior under static loads. Ultimate moment capacity of top and seat angle connections is analyzed through considering each factor which influences the behavior of the joint, the failure of the weakest component will result in failure of the connection. Ultimate moment capacity of top and seat angle connection may be deduced by calculating the resistance of the weakest component of the joint. Initial stiffness of connections is calculated by taking into account each factor which influences the behavior of the joint, in which a cantilever model is adopted to model the top angle when loading, at the same time, a fixed beam model is took to analyze initial stiffness of column flange after preloading bolts. Comparison with test on the connection indicates a good agreement between analytical and experimental results. To simulate the real behavior of connections, finite element analyses are performed through changing connection details. The moment-rotation curve can be obtained by finite element calculation, the effect on ultimate moment capacity and initial stiffness of top and seat angle connections through changing connection geometry parameter can be obtained by finite element calculation either. The results show that the angle thickness, the distance between the axes of the bolt which in tension and the flange of the beam as well as the bolt diameter, along with the height of beam greatly influence the behavior of connections, while, the thickness of flange of the column and web of the column, together with the setting of the stiffener at the web of the column have a litter influence on its behavior. It is also seen that initial stiffness is much affected by the pretension force of bolt.The results in this paper provide suggestion for further study on mechanical behavior of top and seat angle connection and design of the connection.