Collapse Mechanism And Design Criterion Of Steel Beam-to-Column Connection With Cantilever Beam Splicing Under Cyclic Load

Beam-to-column connection with cantilever beam high-strength bolted-splicing in rigid steel frame is widely used in multi-stories or high-rise buildings and industry workshops in the USA and Japan, which is also the recommended connection type in our Technicall Specification for Steel Structure of Tall Buildings and Code for Seismic Design of Buildings. This kind of connection has the combined advantage of shop welding and on-site high-strength bolting, which should have a better energy dissaption and plastic rotation capacity. But its seismic design is traditionally done according to equal-strength method. Little research has ever been done on this kind of connection. Its aseismic superiority has not brought into play. Internationally, only several scholars have put out some theoristic assumes of making use of its aseismic abilities. No validation in experiment, finite element modeling has been ever done. So the analyses of response and collapse mechanism of beam-to-column connections with cantilever beam splicing under seismic load is not only significant from theoretical aspect, but also important in practice.To acquire a perceptual knowledge of this kind of beam-to-column connection, for the first time, cyclic-loading test of four such specimens were carried out, particular attention was paid to the splicing joints. Results showed that the ductility of bolt spjice is much better than welds, weaker splice joints develop larger plastic deformation, slipping between faying surfaces, bearing of bolts to hole surfaces and buckling of splicing plates are all ideal energy dissipation mechanism.Then an thorough computer modeling using finite element program with material, geometry and state triple-nonlinear taken into account is carried out on a series of influencing factors, such as comparison with npn-beam splice connection, comparison of varies designed theories, and the varying of fraction coefficient, diameter, grade, pretension and arrangement of bolts, thickness of web and flanges of beam and column, splicing location, axial loading on column, etc. Lots of useful conclusions are drawn form computer modelling.Finally, design and construction suggestions are given out.This study fills the black in the field of steel beam-to-column connection with cantilever beam high-strength bolted-splicing at both home and abroad. The conclusions drawn can be used to correct some traditionally wrong ideas. Using the suggested design and construction methods can not only save construction materials, but also improve its seismic property. All these conclusions and suggestions will be useful for revising design code, and will lay a foundation for further study.