| Slab-column structure can reduce structure height,shorten time limit of project, and is widely used in the form of low rise buildings in recent years beacaus of it’s concise structure form.Punching failure is usually happened when slab-culumn structure under vertical loads.Punching failure should be strictly avoid in the project because it is a kind of brittle failure.In the actrual situation,slab-column also suffer effects of unbalanced moment when undering earthquake or uneven distribution loads.This kind of situation undering shear and bending moment is a more complex mechanics situation.So puching shear capacity of slab-column under unbalanced moment is a problem worthy to study.The diagonal tension failure theory and shear compression failure theory of beam is discussed first in this paper,and consider that the failure of slab-column conection more consistent with the description of diagonal tension failure theory.This paper described the flexural capacity of slab-column conection based on equal-substitute beam method,and combined with the puching capacity formula in code,a discrimination formula of bending and punching failure is put forward.Comparing with experimental results,the formula calculating results agree well with experimental.This paper compared the calculations of China,USA,UKand Europe.Discussed the characteristics of selection of parameters,control sections and the unbalanced moment equivalent method by each code.Comparison to 36 groups of test results and found the results of Chinese code is much closer to test results than the other codes,and the results are quite safe.But the influence of bending steel is not considered by Chiese code,so the calculation results were high for low reinforcement ratio slabs.4 types test speciments were simulated by finite element software ABAQUS,verify the feasibility of finite element analysis to slab-column.15 types of speciments were also simulated by ABAQUS to discuss the effect by reinforcement ratio,effective thickness and punching span ratio to distribution Proportion for unbalanced moment.According to the above research,calculations for punching shear capacity coefficient η and distribution coefficient α0 for unbalanced moment is suggested,and the calculation results are precise by contrasting the test results.The formula can be used in engineering and and lay a foundation for the further research of slab-column connection. |
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