An Elastic-plastic Comparison And Analysis Of Reinforced Concrete Beam And Slab Structure

This study is to investigate the collaborative working principles of reinforced concrete beam, and understand how the internal force distribution is changing when beam slab structure is in elastic and elastic-plastic state. Based on the series of literature material[38,39,40,41,42,43], the research of the elastic finite element (MIDAS) beam plate element, solid element, the nonlinear finite element (ANSYS) of concrete unit (SOLID65) and reinforced unit(LINK8), this study analyzes15calculation models of multiple layouts of different plate thickness, beam height, span, and the secondary beam.The findings of this research indicate that:there are obvious differences between the internal force of entity unit elastic finite element analysis and that of elastic beam, or plate element analysis, especially in the span of the positive bending moment and negative bending moment of beam support, their analysis of the elastic solid element is about60%of beam plate element; there are greater differences between internal force analysis of nonlinear finite element and beam element——except that the floor of negative bending moment is supported by the frame beam on the outside, the moment of nonlinear analysis of is only about30%-35%of elastic beam plate element in almost all positions; while for the floor of negative bending moment is supported on the frame beam, the nonlinear analysis results about the elastic beam plate element100%-120%, and the maximum bending moment ratio is about1.2-1.6; the main reasons are the plate membrane effect and nonlinear developmental results. The research findings also show that floor of negative bending moment at the supported on the frame beam is about5-8times of the corresponding positive moment, and1.5-2.5times of elastic analysis. Obviously, there are problems of the design guided by internal force of elastic solid element and beam element analysis results to the engineering structure.The study also compares "three-dimensional strip design method" proposed at the literature review [40,41,42, and43],"direct design method" proposed by American ACI, and the side support plate, the elastic design method. The results show that the most rough design method is that of side supporting board; without considering the collaborative working principles of beam slab, negative moment floor positive moment and supported on the beam on the estimate is too large, while the negative moment is supported on the frame beam of the estimate is too small, except the floor supported on the frame beam that leads to negative moment."Direct design method" is closer to the elastic beam analysis results, however,"direct design method" is not used for a beam of the frame beam slab structure."Three dimensional strip method" is closest to nonlinear results, and its application range is wide. Without limitation of "direct design method","three dimensional strip method" is considered to be an ideal and practical design method to the collaborative working principles of reinforced concrete beam.