Experimental Research On Performance Of Beam-column Steel Casting Connections Of Steel Frame

The steel frames is one of the dominating structural system in multistory and high-rise buildings. Moreover, the beam-to-column connections is a key of intensity and ductility of the structures. The performance of connections directly determine the security, reliability, economy and applicability, and so on. But during the 1994 Northridge Earthquake and the 1995 Hyogoken-Nanbu Earthquake a great deal of brittle fractures have taken place in beam-to-column connections, which indicated that the designers on the damage mechanism of some style joints were rather inadequate. In order to avoid the similar damage in future, investigation of some further new and finer joint types of the beam-column connections, analyses of the damage mechanism of new joints types under cyclical load and advance of new aseismatic design measure are not only significant for the theoretical aspect, but also important in practice.In this paper, the experimental study on the steel casting connections which is a new form of beam-column connections of steel frame were carried out. It included three tests of static loading and three tests of cyclic loading.The failure mechanism, failure mode, the law of the stress development on the key parts, moment-rotation characteristics, hysteretic behavior, ultimate strength and initial rotational stiffness of the joints were analyzed in detail. The effects of several factors on the change of the thickness of the vertical and level of limb of the cast steel were studied. The behavior of ductility, energy dissipation and stiffness degradation of steel casting beam-column connection were also researched. Finally, formula of calculating the flexural strength of the cast steel connections was gained on the basis of the simple plastic theory.The results of this research indicate a lot of useful information. Firstly, steel casting connection is a typical semi-rigid connection, which not only has high initial stiffness and ultimate moment resistance but also shows good ductility and energy dissipation. Secondly, the geometry parameter of the steel casting connections is the major factor in relation to the connection behaviors Thirdly, steel casting play the role of dissipated energy well by self-buckling, so it's feasible to design the steel casting as a energy dissipation component. Fourthly, with the thickness of he vertical and level of limb of the cast steel increasing, the connections of rigidity, bearing capacity and seismic performance is also enhanced. Finally, it is reasonable to simplify the steel casting as rigid frame model according to the distribution of plastic hinges and deformation characteristics of the steel casting when the connection destroyed in the test.