Simulation Analysis On The Progressive Collapse Resistance Of Spatial Coordinated Interaction Among Beams,Columns And Plates Of R.C. Frame While Considering The Effects Of Parameter Changes Of Plates

In a study of the progressive collapse resistance of spatial coordinated interaction among beams,columns and plates of R.C. frame while considering the effects of parameter changes of plates,the nonlinear finite element method based on degenerated solid virtual laminate element theory is introduced;by using this method to a single R.C. slab-column structure,trials of anti-collapse of the whole process simulation are carried out, and results obtained are basically the same with experimental results,the rationality and applicability of the method has been verified in the description of R.C. slab-column structure collapse process.Then have a comprehensive comparative analysis of the results of structures which consider the overall effect of the plate and without considering the overall effect of the single frame structure,and two models with the softest and stiffest plate among nine models based on orthogonal test design ideas(three-parameter and three levels)by static nonlinear analysis while removing components of the structures;and a comparative analysis of ultimate bearing capacity of nine orthogonal models in the removal of columns at different regions is carried out.Throughout the analysis found that the plates of structure have a significant performance impact to the collapse properties,the impact reflected on level or vertical displacement of the structures or components,the structural collapse mechanisms and alternative load path;the stiffer the plates,the less torsion components which coupled with the failure column have;however,if the plate is too rigid,it will inhibit the emergence of the beam hinge,although enhanced structural integrity, but ductility unfavorable;the study also found that when the plate is rigid,the leading of beam and plate mechanism is changed from beam guidance to plate guidance,when dismantling the central column of the structure,plates in collapse region form a big bidirectional board,beams act like stiffeners effect;when the reinforcement ratio of the plates within a reasonable range,the effects of the thickness of plates are most sensitive to the limit load of structures,the reinforcement ratio of the bottom of plates followed,the reinforcement ratio of the top of plates has the lowest rates.Then,a four-floor frame model is established while considering the overall effect of plates based on the single-layer model which mentioned previously.By removing the components,it is found that the ultimate bearing capacity increased more significant while increasing the rigidity of the plates when removal of the corner column,followed by removal of side column,and finally dismantle central column situation.When dismantling the central column of the structure, the time failure mechanism of layers appear delayed from the bottom to the top,the delay process is very short in the removal of the corner column.Finally,some optimization on progressive collapse design suggestion was put forward based on a comprehensive analysis of the progressive collapse resistance performance of the single and multistory R.C.frame structures.