Analysis On Extended Endplate Semi-rigid Connections Under Seismic Loading

In the steel frame design, design of joints is the key. The anti seismic ability of steelstructure mainly comes from structural damping and the structure of the plasticdeformation capacity. The rigid connection steel frame beam column joints can usually bereduced structures horizontal displacement that generated by the lateral loads, but throughthe earthquake research results show that, using the low ductility rigid node causes thenode to appear brittle fracture before the beam and column, the well plastic deformationability of steels can not fully show up. Therefore, the design of steel frames usesemi-rigid connections usually, the semi-rigid connection has well plastic deformationability, under the action of earthquake，it can increase structural damping, prolong theperiod of the structure, reduce the amplitude, it is an ideal seismic design node. Thispaper studies the extended end-plate bolted connections is a kind of semi rigid connection.As a result of end plate connection research data is relatively scarce, the theory is notperfect, so the analysis of extended end-plate bolted connections about the failuremechanism and energy dissipation capacity under cyclic load has important significance.In this paper, the nonlinear finite element simulation is considering geometricnonlinear and material nonlinear factors, as well as the nonlinear contact conditionbetween the adjacent panels. The research designed11extended end-plate boltedconnections simulations under the monotonic loading and the cyclic loading, the testconsidering the influence of node energy consumption performance and the bearingcapacity factors are the thickness of end-plate, bolt diameter, thickness of column flange,and the axial pressure at the top of column, end-plate stiffener, and column stiffener.Cyclic loading test results show that the extended end-plate connection hysteretic curve(M-θ) are relatively well-stacked, the energy dissipation coefficient is greater than2, theconnections has a good seismic performance. However, the different structure factors thatmay influence the node energy dissipation capacity and the bearing capacity of theconnection. Such as increasing the thickness of end-plate can improve the energydissipation capacity of joints, setting stiffeners and end-plate stiffener can significantlyincrease the load-carrying capacity and energy dissipation. In this paper, through theanalysis of different structural forms result in destruction of the nodes and the hystereticcurve, obtained a series of basic conclusion. Based on the " strong column and weakbeam, strong connection and weak constructional element" seismic design train of thought, put forward extended end-plate bolted node seismic design suggestions, as thisnode provides the reference for practical engineering application.