Behavior Of High-strength Bolted Endplate Connection Steel Structure Under Monotonic And Cyclic Loading

A Steel structure consists of steel as the fundamental material. Such a structure is commonly used worldwide because of its advantages such as high bearing ability, small cross-section, and low net weight. Beam-to-column connection is one of the most important aspects in the design of steel structures since the reliability and efficiency of the connection have great influences on the overall behavior of the structures. Analyses on earthquake disasters, in recent years, have shown that often times, a traditional beam-to-column welded joint does not achieve the ideal seismic resistant state and dissipate the energy quite effectively (with connection cracks usually appearing before the plastic hinges formed on beams). Therefore, more and more attention is being paid to high-strength bolted endplate connection joints because of their better reliability, and since the connections can play the role of plastic hinges. An important advantage of the connection is good ductility, making it seem to be ideally seismic resistant. Researchers in China and abroad have laid emphasis on the working behavior of high-strength bolted endplate connection joints, and this topic is currently of great interest.The formulation of high-strength bolted endplate connection joints decides its high bearing ability and ductility to some extent. It belongs to a kind of semi-rigid connection and therefore, considered unsafe and not suitable according to traditional steel frame design, which is based on the principle that connections are fully rigid or ductile. Moreover, the research on the behavior of high-strength bolted endplateconnection joints is in the beginning phase. Therefore, the analysis of high-strength bolted endplate connection joints under both monotonic and cyclic loading is really of significance.In this paper, based on the recent investigations, 3-D nonlinear analysis models have been devised according to the interactive mechanical characteristics of each component constituting the high-strength bolted endplate connection joints. A model for the fully welded joint model has also been constructed for the sake of comparison.With such models, a total force-displacement process for both high-strength bolted endplate connection joints, with and without stiffener, and welding has been studied. A detailed analysis of M - 9 curves has also been done. The study includes stress arrangement mode, the trend in the development of stress and strain on the bolts, displacement and failure modes on connection components under monotonic loading; and the earthquake energy dissipation and ductility response under cyclic loading. The factors affecting the joint's cyclic behavior are thus deduced by analyzing the data.Finally, two numerical examples of actual experiments have been cited to check the accuracy of the analysis and the reasons for the differences in data discussed. The results confirm the accuracy of the 3-D nonlinear analysis models, and their reliability to satisfy practical projects. This paper therefore, attempts to provide an insight into the design of high-strength bolted endplate steel structures serving under monotonic and cyclic loading conditions.