Study On Structure Progressive Collapse Mechanism Of Space Steel Frame

The design of building structures tend to ignore the impact of unexpected events, withoutconsidering the adverse effects of accidental loads. In case of emergency accidental load leadsto the failure of structural bearing component, how to reduce structural progressive collapsefailure，prolong the maintaining stability of the time of structure system is the difficulty ofresisting progressive collapse. This paper uses finite element analysis software SAP2000toanalyze the progressive collapse behavior of a four-story steel frame structure with aload-bearing column failure. The main contents and conclusions are as follow.(1) By demolishing component method, the four-story space steel frame structure take:linear static analysis, linear dynamic analysis, nonlinear static analysis and nonlinear dynamicanalysis. the various methods have different ptacticability, linear static analysis with dynamicmagnification factor2can equivalent simulate structural dynamic effect; linear static analysiscan be simple, effective for simple structure progressive collapse analysis; Nonlinear dynamicanalysis can accurately simulate the progressive collapse.(2) By using the Alternate Path Method in the nonlinear dynamic condition to analysis ofthe plastic hinge of beam, failure node displacement-time history curve in different position ofbearing column failure can find that plastic hinges only occur in the upper floors of failurecolumn; the higher floors the failure column at, the higher degree of development of plastichinge, the greater displacement of the failure point, the greater the plastic rotation of the beam;the removal of the prism is most harmful to the progressive collapse destroyed.(3) The analysis of the structure internal force changes under different position bearingpillar failure on different floors, explore the internal force (axial force, bending moment andshear) distribution form of column and beam in the process of progressive collapse, researchshows that within the internal column, corner post of the framework, the remaining structuralcolumn elements will compression failure; the farther distance away from the failure column,the smaller change of the internal force; the internal force of column and beam is reversed up the failure column; After a load-bearing column failure, the internal force of the remainingstructure will reach the maximum value within0.2s, the probability of progressive collapse ishigh in this period.(4) Study the effects of plastic deformation and the vertical displacement of the failurepoint. Research the length of the load-bearing column failure time, member of the floors forthe impact of the progressive collapse damage, the shorter the the load-bearing column failuretime is, the worse damaged of progressive collapse the structure is; changing the number ofthe floors of the structure have no significant effect on the progressive collapse destroyed;...