Analysis Of Progressive Collapse Resistance Capability And Reliability Of Reinforced Concrete Plane Frames Based On OpenSees

The so-called progressive collapse failure,is the failure of the main supporting member in the structure under accidental load,which causes partial collapse or collapse of the whole.In this paper,the nonlinear static Pushdown method is used to analyze the progressive collapse capability of RC plane frame after removing column,and a new method for calculating the reliability of frame structure is proposed.(1)In this paper,by means of OpenSees finite element software,the pseudo static test of the structure is simulated from three levels of constrained beam,single-layer plane frame and multi-layer plane frame,and the reliability of OpenSees finite element model is verified for the mechanism of arch,transformation and catenary mechanism simulation.(2)Taking 4 span reinforced concrete plane frame as research object,the paper compares the Pushdown curves and the axial force curve of the frame beam of different floors,different positions of floor,different plane positions,different floor height and different side spans,and discusses the influence of different parameters on the bearing capacity of the arch and catenary mechanism.In fact,the change of the floor number above the moving column and lateral stiffness is the key to the ability of the frame structure to resist progressive collapse.(3)Through the analysis of the axial force of the frame beam during the progressive collapse,the stress mechanism of the frame structure at the stage of arch and catenary mechanism is studied,and the mechanism and action of the Vierendeel action of the frame structure after the column moving are expounded.The frame beam immediately above the moving column is an important component of the whole damaged structure.(4)Based on the finite element numerical simulation of OpenSees,a method for calculating the reliability of RC plane frame structure system is proposed on the basis of ultimate bearing capacity.The load-carrying capacity of the Pushdown curve is calculated and the bearing capacity of the arch mechanism and the limit state catenary mechanism is compared.The system condition failure probability is calculated by the series system,and the relationship between the frame beams is set up by the relative size of the tension bar strain of the frame beam,which is used to adjust the load effect of the frame structure.The results show that with the increase of the number of layers above the moving column and the decrease of the lateral stiffness of the frame beam,the bearing capacity of single laminated arch mechanism and catenary mechanism decreases gradually,and the failure probability of the structure system increases.