| During the process of using building structures,structures may bear accidental loads,such as explosion,impact and so on.If the residual structure can not effectively bear the unbalanced load or the internal force change caused by the initial damage,the residual structure will be further destroyed,which may trigger domino effect what may cause the large-scale damage and even the whole structure of the progressive collapse.At present,most of the research are based on single analysis method to analyze the anti-progressive collapse.Based on the analysis platform of SAP2000,this paper introduces the collapse criterion of foreign codes,also uses linear static and nonlinear dynamic analysis methods to analyze the progressive collapse resistance of RC frame structures based on the current China codes.The main research contents are as follows:（1）In this paper,SAP2000 finite element software is used to model the shrinking scale experiment of reinforced concrete beam-column structure.By comparison,the modeling method,material constitutive model and element selection in finite element software are verified,which lay the foundation for the later research.（2）Based on GSA2016 and Do D2016,a five-story RC frame model is built by SAP2000.Different working conditions are set up for removing different pillars,the linear static and nonlinear dynamic analysis methods are used to analyze the progressive collapse of the structure.The linear static collapse parameter DCR and the nonlinear dynamic collapse parameter are introduced.The results show that the DCR value of the residual structure is less than 2 when the linear static analysis method is used.When using nonlinear dynamic analysis method,the maximum displacement of demolishing corner columns is 0.0243 m and demolishing short-side central columns is 0.0135 m which does not reach the maximum displacement of the failure of the members and meets the requirement of resisting continuous collapse.Through comparative analysis,the maximum vertical displacement of linear static analysis is 10.3%～19.0% higher than nonlinear dynamic analysis,the bending moment value of linear static analysis is17.2%～24.3% higher than nonlinear dynamic analysis,which indicates that the results of linear static analysis are conservative.（3）By introducing Dynamic Increase Factor,SAP2000 is used to investigate the influence of the progressive collapse resistance and Dynamic Increase Factor of RC frame structures that caused by the number of structural layer and failure time under different column removal conditions.The results show that the risk of continuous collapse of RC frame increases with the increase of the number of floor.The effect of the number of failure layer on Dynamic Increase Factor can be neglected.The DIF value of demolishing long side pillar is larger than that of demolishing short side pillar.Compared with the Dynamic Increase Factor suggested by CECS 392,the DIF value of demolishing the long side middle columns is basically consistent with it,and the DIF value of demolishing the short side middle columns is slightly less than the suggestive value.With the increase of failure time,the risk of resisting continuous collapse decreases.The structural failure time can significantly affect the Dynamic Increase Factor of the structure and the performance of the structure against progressive collapse.The dynamic response of the structure can be reflected best when the failure time is between 0 and 0.1T. |
