Study On The Semi-rigid Connections And Progressive Collapse Performance Of Steel Structures

The isotropic steel material has a very high tensile strength and performs well in ductility, which make sure the steel structure possess plenty of warning time in case of structural collapse. Thus, as the using of steel material getting popular, the more attention has been drawn in the field of the steel framed building’s anti-collapse ability. In order to simulate the progressive collapse process of steel framed building and estimate the anti-progressive collapse potential of it, the real behaviour of connection should be taken in to consideration during the analysis procedure. After applied with a certain load, a connection within the steel framed building would usually performed a certain displacement, which is called the semi-rigid behaviour of the connection. Therefore, the research of the steel semi-rigid connection’s performance and its simulation would benefit the accurately analysis of the steel framed building’s anti-collapse ability. Thus, the main researches included in this paper are listed as followed:1. Research of T-stub under tension was carried out, and improvement of the T-stub nonlinear multi-spring component model has been made in this paper. In order to calibrate the proposed T-stub component model, tests and FEM analysis have also been introduced, which demonstrated that the proposed T-stub model as well as FEM model can efficiently describe the T-stub nonlinear behaviour when loaded.2. In this thesis, an overall review has been made in the field of the connection research, especially the semi-rigid connection, the computing method and its analytical model. By comparing several exist analyzing methods, author proposed a multi-spring model of the semi-rigid connection basing on the T-stub component model. Through comparing to test results and analysis results of 3D finite element model, the validity of the semi-rigid connection multi-spring model has been demonstrated. The works above made the accurately and effectively analyzing of the steel framed structure with considering real connection behaviour possible.3. An elastic-plastic analytical method of double-span steel structure suffering middle column loss with considering the catenary action effect was proposed. By introducing the concept of energy conservation, the proposed double-span steel structure model could make structural dynamic analysis with both accuracy and efficiency. By taking catenary action effect into consideration, the extreme load carrying capacity and the corresponding deformation of the structure can be obtained with accuracy, which would provide a solution for building anti-progressive collapse design in practice.4. After accurately described the semi-rigid beam-to-column connection’s real behaviour and the double-span steel structure’s anti-collapse ability when suffering middle column loss, the progressive collapse resistance of the steel framed structure can be estimated, so as to conduct preliminary simulations and parametric study of simple steel framed buildings. By establishing and analyzing 2D and 3D FEM model of steel framed building suffering sudden column loss, the influences of the joint property, the fail location, the column loss analyzing time and the brace performance on the dynamic response of the frame and the connation were discussed, basing on which the structural reinforce method of buildings has also been presented.