Experimental Study And Theoretical Analysis On The Increasing Beam And Removing Column Connection

The study on connection is an issue of great concern in steel structure. According to the differences in the load transfer, connection mode and details, the connections with different mechanical properties are classified into three kinds: rigid connections, semi-rigid connections and hinge connections. At present, most focus is put on the study of semi-rigid connection, while there is so little attention on the study about hinge connection that there is still no judgement standard available in the construction. Under the project background of "the 460 pipe processing factory increasing beam and removing column project" of Tianjin Pipe (Group) Corporation (TPCO for short), the experimental and analytical study on a new connection—increasing beam and removing column connection were carried out.The principle of connection design was introduced briefly and study situation on connection was analysed. With the brief introduction on the project background, the main work of this paper was put forward.Some connections and the judgment standard at home and abroad were introduced. According to the research content in this study, the connection mode, advantages and disadvantages of five hinge connections were emphatically analysed to lay a theoretical foundation on this paper.Based on the project background, the reduced scale models of connection were built with ANSYS according to the reformation form and structure. Taking the favorable influence of the column capital slab on the connection, the theoretical analysis of connections was carried out, with which the failure mode was confirmed and theoretical capacity was obtained, providing reference for the experiment.In order to deeply study the performance of the reformed connection, the quasi static experiments of reduced scale modes were designed and carried out. Based on the experimental results, the hysteresis loops, skeleton curve, energy dissipation coefficient and degradated stiffness coefficient were analysed with the experimental and analytical results compared. It is proved that the performance of connection was obviously hinged after reformation, including the poor energy dissipation capacity and the severe stiffness degradation,According to the experimental study and theoretical analysis, the simplified spring model was put forward and the relation between the rotational stiffness and the effective connection length of beam-column was studied. The effect on the behavior of connection under the different reformation form was studied and the quantitative relation was got by the optimal analysis. The method of EC3 and Bjorhovde were used to determain the connection classification and it is confirmed that increasing beam and removing column connection should be categorized as hinge connection. Furthermore, it is put forwards that the connection with rotational stiffness less than 25% of that of original rigid ones should be regarded as hinge connection. That can be considered as a judgement standard of hinge connection in actual engineering.