The Analysis Of Antiseismic Behavior Of Beam-to-Column Web Connections And Dogbone Connections In Steel Moment Frames Under Cyclic Load

As important parts in steel frame, beam-to-cloumn connections play a vital role in transferring of 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 great many brittle failures of beam-to-column connections, which indicated that cognitions of people on the stress behavior and damage mechanism of beam-to-cloumn connections were rather inadequate. In order to avoid the personnel casualty and the property damage, to study damage mechanism of beam-to-column connections under cyclical load and to propound new joints requirements and antiseismic design measures have important theoretical signification and engineering value.At present, many researches are concentrated on beam-to-column flange connections, there are only a few researches on web connections. Now, correlated specifications in China mostly aim at flange connections, and design gauge rules connecting to web connections are very few. Therfore, the major study project of this paper aims at beam-to-column web connections.In order to simulate fracture mechanism of beam-to-column web connections under seismic load, large deformation, large strain, high-strength bolts pretension and touch slippage are considered in FEM. Mises yield rule and multilinear hardening model of stress-strain are adopted in FEM, and crack index is applied to analyze connection fracture.After verifying rupture rule and numerical model, for basic specimens and derived serials of specimens, the influences of parameters of these specimens such as bolts diameter and their arrangement, column flange width and pressure on column on connections are studied. Under monotonous load and cyclic load, the stress behavior and hysteretic behavior are non-linearly simulated, and the stress field of critical position simulated are analyzed. According to analysis results, some references are given out for engineering design.On the basis of damage mechanism of traditional beam-to-column web connections, the parameters of new type of dogbone joints are studied, the influences of weakened three parameters on stress behavior are discussed, and the advice for improving the antiseismic behavior of dogbone joints are obtained.The FEM of this paper could well simulate the failure behavior ofbeam-to-column joint and dogbone connections under cyclical load. The study content is rather comprehensive and systematic. The conclusions and design recommendations have important reference value on engineering design.