Mechanical Study Of The Cover-Plate Reinforced Connections In Steel Frame

The cover-plate reinforced connection studied in this paper is one typical kind of beam section reinforced forms. By welding a cover-plate at the beam-end, the cover-plate reinforced connection achieves the purpose of moving the plastic hinge far away from the beam and column interface that will improve the mechanical behavior and protect the connection.This paper firstly reviewed the study history of the cover-plate connection, and then made out the design process based on the American standard FEMA-351 and ours. It also established the finite element models of the former test samples and compared the results. Two finite element analysis models groups (CPC-A and CPC-B) ware founded to respectively detail cover-plate geometry affect to the connection mechanical behaviors.The result of experiment and ANSYS simulation shows: the plastic hinge is successfully formed in every sample, and they have a high consistency in stress development, failure mode, ultimate load, hysteretic and ductility behavior and energy dissipation. The high consistency proved the success of experiment and the correctness of the ANSYS finite element simulation.Through the study of changing the cover-plate geometry we can get the following conclusions: the plastic hinge locates at 0.3～0.4 beam depth from the cover-plate end. Increasing the length of cover-plate could raise the ultimate load greatly, and will raise the hysteretic behavior and the energy dissipation, but lower the ductility behavior. Cover-plate with short length will not play an effect role in moving the plastic hinge away from the connection area, and the long length will make the cover-plate and the panel zone stress in a high degree. The suggested length is range 0.5～0.75 the depth of the beam. Increasing the thickness of cover-plate will not raise the ultimate load, hysteretic behavior and the energy dissipation apparently, but will lower the ductility behavior of the connections. The thinner cover-plate could not play a role in reinforcing the connection, and the too thick cover-plate will make the weld too high at the beam and column interface. The suggested thickness should higher than the calculate value and lower than the beam flange.