The Progressive Collapse Analysis Of Steel Beam To Concrete-filled Steel Tubular Column With Ringlike Plate Connections

Base on the finite element analysis platform of ABAQUS,the fine element model and multi-scale model were used to analyze the anti-progressive collapse performance of the steel beam to concrete-filled steel tubular column with ringlike plate connections in this thesis.The main research works which have been done are listed as follows:(1)Based on the secondary development interface of ABAQUS,the concept and calculation method of the fiber model were introduced to the finite element analysis platform of ABAQUS.A fiber model program iFiberLUT was developed in this thesis,which can be used to analyze the quasi-static,elasto-plastic and progressive collapse resistant performance of steel structures,reinforced concrete structures and steel-concrete composite structures.The developed fiber model contains an ABAQUS Fiber Generator which can discrete the fiber of cross-section automatically,and the iFiberLUT material library includes different concrete,steel and reinforcing bar uniaxial hysteresis material constitutive models.And the effect of different steel material models on the calculation results of structures and reasonable element numbers were discussed.(2)Utilizing the fine method model,the nonlinear static analysis method was used to analyze the performance of anti-progressive collapse of the steel beam to concrete-filled steel tubular column with ringlike plate connections.In this thesis,the failure patterns,resistance mechanisms of progressive collapse and the variation rules of internal forces of typical joints were studied.And this research also analyzed the influence factors of the performance of anti-progressive collapse of typical joints,including Geometry and material parameters.Among these influence factors,the material strength of steel beam and steel tube,steel ratio of the column section,the width of ringlike plate and the height of steel beam have various degrees to raise anti-progressive collapse ability of the steel beam to concrete-filled steel tubular column with ringlike plate connections.However,the core concrete strength has minimal effect on the capacity to resist progressive collapse.(3)The multi-scale model,combined the developed fiber model with the fine element method,was used to research the performance of typical joints by using nonlinear static analysis method.Meanwhile,this study also took into account the influence the adjacent framework of the typical joints.By analyzing the ability of progressive collapse,failure modes and stress distribution,the conclusion,that the adjacent framework can irnprove the ability of anti-progressive collapse of the typical joints,is obtained in this thesis.(4)By using the multi-scale model,the vertical displacement time history curves of typical joints were obtained with the nonlinear dynamic analysis method.The relationship between resistance and resistance demand of typical joints were obtained by comparing the nonlinear static analysis results with the nonlinear dynamic analysis results.These comparisons have showed that the frame structure with the typical joints,which enable to form the bridge mechanism and new alternate path of unbalanced loads,cannot occur as progressive collapse after the failure of column conjoint typical joints.(5)Based on the acceptance criteria for in GS A2003 and by the comparison of nonlinear static analysis compute results,the research have showed that,before the vertical displacement of typical joints reached acceptance criteria,the two circular section style joints and the steel beam to concrete-filled steel tubular column with penetrated ringlike plate joints had fractured at the section of beam to ringlike connection,and bearing capacity declined rapidly.Therefore,the acceptance criterion for in GSA2003,which is used to judge whether the joints have took place progressive collapse,is inadequate.The real ultimate bearing capacity of material should be considered in the evaluation process.