Fracture Behavior Analyses Compared Dog-bone Connection With Traditional Connection

After the1994Northridge earthquake and the1995Kobe earthquake, peoplediscovered that numerous steel structure building occur brittle fracture at the beam tocolumn connection. Subsequently, experts present many improved connection, thereduced beam section connection is one of them, through reduced the flange of beamto improve the connection’s anti-seismic performance.In order to study the dog-bone connection’s anti-seismic performance and fracturetoughness requirement, in this paper, through the software-ABAQUS6.10, establishedthe full size of dog-bone connection and traditional connection’s3D finite elementmodel, obtained the beam to column’s hysteretic curve under low cyclic repeatedhorizontal loading. The theoretical analysis indicated, the reduced beam connection’senergy dissipation is better. For the elastic and inelastic analysis of the dog-bone andtraditional connections’ fracture properties, use the stress intensity factor KIand GIintegral as evaluation index. The results indicate that, at the elastic stage, therequirements of fracture toughness at the middle of welding line along the beamflange is the biggest, while at the edge of welding line, the requirements is relativelyhigh. Along the beam flange, the dog-bone connection’s fracture toughness is almostthe same with traditional connection. At the edge of reduced beam section, fracturetoughness requirements are the biggest along the beam flange. It appears stressconcentration at the edge of the reduced beam section. While at the inelastic stage, theJIintegral at the edge of the welding line is bigger than the middle’s, this can easilyexplain why the edge of the welding line is first crack. The inelastic and elastic stageare quite different, through reducing the beam flange the dog-bone connection’srequirements of fracture toughness are obviously reduced than the traditionalconnection’s. Among the reducing parameter, the connection’s fracture toughnesswhich reduced50%is the lowest, but the analysis indicate that, connections whichreduced50%, the flexural capacity are reduced obviously, so the parameter is betterto under25%, the same with FEMA’s proposals. Then, the dog-bone connection notonly reduce the requirement of fracture toughness, but also its’ flexural capacity canreach the flexural moment when the whole section yield. So the dog-bone connectioncan play a role as fuse, realize strong joint weak pole, strong column weak beamdesign concept.