Study On The Performance In The Earthquake Effect To The Connection Which Is Weakened In Beam And In Double Directions

Beam-to-column connections play a vital role in transferring moments and shearing forces, and their behaviors directly affect the overall behavior of steel frames. In the 1994 Northridge earthquake in America and 1995 Hyogoken-Nanbu earthquake in Japan, there were many brittle failures of beam-to-column connections. In order to avoid the personnel casualty and the property damages, many new connections were carried out by home and abroad experts.The new connections are kept showing, mainly contain two types, one is strengthen type, the other is weaken type. The former one means strengthen the connection zone and connections' intensity, but weld numbers of connection zone will increased, meanwhile, defects conducted by weld will increased; the latter type means to get somewhere of the beam weaken in order to make the plastic hinge come up earlier than the time when brittle fracture showed at the welding. That will be like an fuse. The weaken type are mainly expressed as flange weaken connection and web weaken connection, the later is better than the former in the loss of the bearing capacity.However, so far the mainly research of beam-to-column are about the strong axis, which is the connection on the strong axis of column, and the research on the web connection of beam-to-column, that is weak axis of column connection is less and most of the codes is aimed at flange connection, the codes to the designing of web connection is a little too.Aim at the question above, beam with the weak axis is improved, that means the way to weaken the connection is to drill a hole on the web, this can control the position of plastic hinge and time to form it, which can have an effect to protect the welding line under earthquake load. And then put this connection in double directions to study the effect to the weak axis connection under double direction load.Establish and analyze the model by ANSYS software. The result shows, that have a reasonable hole on the web of beam with weak axis can control the form of plastic hinge and protect the welding line. Last but not least, the reasonable size and position of the hole were advised, and the weak axis connections are damaged easily in double direction connection. So the effect of double direction in the connection should be considered while designing and doing research.