Mechanical Properties Of Beam-to-column Connections With U-shaped Dampers

The traditional view is that bolted-welded combined beam-to-column connectionshas good seismic performance, therefore these connections have wide application inengineering practice. However in the1994Northridge earthquake and the1995Kobeearthquake all the steel framework using this type of bolted-welded combinedconnections occured the unexpected brittle failure, it caused the attention and study ofmany scholars. In this paper, the author puts forward a new type of jiont with U-shapeddampers for beam-to-column strong axis connecting, these jionts are connectedthrough U-shaped dampers at the place of bottom flange and web, this type ofconnections are semi-rigid connections, and this type of connections have largedeformation ability, good performance of energy consumption. Under the action ofload the destruction of connections mainly concentrated on the dampers, repair thistype of connection only need to replace the dampers can achieve the purpose ofrepair connections.This paper analyzes the mechanical properties of the U-shaped damper at first,deducing the formula of initial elastic stiffness and ultimate load of U-shaped damper,and through the finite element software to establish four groups of U-shaped dampermodels for monotonic loading analysis, through comparing the results of finiteelements analysis verified the feasibility of the theoretical formula.Secondly, the seismic performance of beam-to-column connections withU-shaped dampers are studied based on the finite element analysis software Abaqus,including hysteretic performance, stiffness, bearing capacity and stiffness degradation, failure mode, etc. At the same time, the effect of the thickness, height, radius ofU-shaped section and thickness of flat section to the seismic performance ofconnections were analyzed. The results show that:(1) under the action of load,U-shaped dampers first occur yield and failure, while the beam and column remainedintact after earthquake, we just need to replace the U-shaped damper can achieve thepurpose of repair connections;(2) this type of connections have large deformationability and capacity, and have good hysteretic performance;(3) the sectionalspecification of U-shaped damper has a great impact on the performance ofconnections.