| Previous investigations of earthquake disaster indicated that many damages occurred in the steel frames to various extents, and mostly belonged to brittle fracture of beam-to-column connections, which indicated that cognitions on the damage mechanism of welded-bolted beam-to-column joints were rather inadequate. The engineering circles, consequently, have been reach agreement. That is, the ductility of the connections ought to improve and the ductile design on steel frame should be realized. The development of steel moment connections with reduced-beam sections is addressed. And the RBS' s details are proposed to obtain strong column weak beam. It has been proved that the performance on steel moment connections with reduced-beam sections reveals the perfect ductility of the connections by the experimentation research and the engineering practice. In fact, beam-to-column web connections are as widespread as flange connections in the steel frames, the principle of strong column weak beam upon the aseismic performance of steel moment resisting frame works as the same in the beam-to-column web connections design. However, the relative studies concerning the beam-to-column web connections develop quite inadequate and deficient. Accordingly, studies on seismic-resistant behavior of the RBS' s beam-to-column web connections are not only significant from the theoretical aspect, but also important in practice. In order to predict the fracture mechanism of the RBS' s beam-to-column web connections under seismic load, an updated Lagrange finite element formulation involving large deformation, large strain, steel hardening model under cyclical load in reality, as well as status nonlinear in order to predict high-strength bolts pretension and contact-friction in contact zone, is adopted in FEM Model. This FEM model involves steel ductility fracture criterions and brittle fracture index and reflects beam-to-column joints under cyclical load in reality. According to the recommendations of the American seismic provisions upon the RBS' s connections, which by Seismic Provisions for Structural Steel Buildings published in 1997, and combining present code and actual requirements of the engineering,this article is mainly by the procedure ANSYS6.1 to calculate and analyze the RBS' s finite element Analysis models designed by changing the RBS' s dimension parameter which are three team and total fourteen models, and post the measures with reason upon the beam-to-column web connections with reduced-beam sections. In conclusion, the finite-element model can well simulate the behavior of the RBS' s beam-to-column web rigid connections under cyclic load. The study is rather systematic. The conclusion and design recommendations are very useful for instructing the project. This article plays a basis role of more study with regard to seismic-resistant behavior of the new type beam-to-column web connections.
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