Seismic Performance Analysis And Comparative Study Of Structural Ductile Joints

After the Northridge earthquake and the Kobe earthquake, brittle failure occurred on most of the beam-column connections in steel frame, which had been considered to be provided with excellent aseismatic performance by most scholars. Since that, many kind of ductile connections against earthquake have been studied by scholars from various countries. Under the condition of strong column and weak beam, the weaken connection and the strengthen connection were put forward. Based on previous study on dog-bone connections and wide flange connection, reinforced dog-bone connections is put forward, and analysis and comparison of mechanical performance for these connections will be studied in this article.During matrix displacement method in structural mechanics, components of the force on connection are combined into matrix, and then element stiffness matrix of normal rigid connection(NOR), dog-bone connection(RBS), wide flange connection(WFC) and reinforced dog-bone connection(FRD) are put forward. It can be concluded that changes in connection stiffness make great influence on shear stiffness coefficient and flexural stiffness coefficient of the weaken connection, and overall and outer stability of connections can not be neglected.Though finite element software ABAQUS, static cyclic loading and dynamic load are applied in these connections and the mechanical performance can be analyzed.First, four separate beam-column connections are designed, which will be acted on static cyclic loading. During calculation of the finite element software, mises stress nephogram in elastic deformation stage and plastic deformation stage can be acquired, and the hysteretic curve, stress path, energy-dissipating capacity, rigidity degeneration can be analyzed and compared. Through analysis of the formation and development trend of connection plastic hinges, it can be concluded that, for reinforced dog-bone connection, the plastic hinge can go away from the beam and column interface with sufficient bearing capacity.Secondly, one-bay steel frame for6floors,9floors,12floors were established during finite element software. Modal analysis is used to these models and natural vibration period for first ten modes can be calculated. It can be concluded that, changes in connection stiffness make more influence on frame stiffness with the increasing floors.Finally, for simulateseismic intensity8under rare occurrence earthquake, ElCentro and Taft waves are applied on the steel frames during finite element software ABAQUS, and Vertex relative displacement-time and base shear-time curves of every steel frames can be drawn. It can be concluded that, vertex relative displacement-time and base shear-time curves of steel frame for6floors,9floors are almost on the same tendency; for12floors, obvious difference occur on the curve. The changes of stiffness of reinforced dog-bone connection and normal connection are similar. For steel frame with reinforced dog-bone connections, low base shear can be realized with the condition of low story drift and enough bearing capacity.