Research On Shear Strength Of RC Beam-Column Interior Joints Based On The Bayesian Theory

For a long-term, in order to study the performances of joint shear, a large number ofreinforced concrete (RC) frame joint shear tests were carried out by the scholars. And a seriesof semi-empirical formulas of calculation for joint shear strength were put forward based onthe abundant experimental data. It has become a major direction of research on joint shearperformances to seek the calculation models of frame joint shear strength that agree betterwith the experimental results based on the re-understanding and recognition of the abundanttest data and analysis of the main influencing factors of RC frame joint shear performance.The main content of this research is to apply Bayesian theory to construct calculationformulas for RC frame joint shear strength. Compared with the traditional frequency method,the Bayesian approach makes the full use of the information provided by the sample and theprioror. So in the point estimation, the Bayesian estimation can get better precision. This studyprovides a useful theoretical method for the research on the performances of framework jointsshear, and for more in-depth understanding of frame joint shear capacity has the importanttheory significance and has important theoretical significance and practical value for a morecomprehensive insight into the shear capacity of the frame joints.In this paper,101groups of shear test for frame interior joints under low-cyclic loadingin different historical stages are collected as the information of Bayesian estimation, the testdata were collated and analysed, and then selected a prior model. Two types of theinformation, the epistemic information and the sample information, are synthesized byBayesian approach to estimate the unknown model parameters. And the univariateprobabilistic models for shear strength of the RC beam-column interior joints are constructedand the prior models are updated. The major contributions of the work in this thesis are listedas follows:1. RC frame joints stress mechanism and the main influencing factors of joint shearstrength are analysed. The test results of frame interior joints under low-cyclic loading arecollected and analysed as the experimental database.2. A prior distribution (It is non-informative prior distribution in this paper) is firstlyselected to establish calculation models of RC frame joint shear strength. The process issynthesizing the prior information with the sample information to estimate the unknownmodel parameters by Bayesian theory to get the specific calculation model. All theinfluencing factors of joint shear strength are considered in the calculation model. 3. In consideration of some factors’ impact on interior joint shear strength is notsignificant, stepwise regression process is applied to weed out the influencing factors tosimplify the calculated model above.4. Last, the calculation results of the simplified model are compared with that of shearstrength formula in current code to illustrate the advantages of simplified model.The study shows that the calculation results of RC frame interior joint shear strengthformula based on Bayesian theory agree well with the experimental results and more close tothe the experimental results compared with the calculation results of the recommendedformula in ACI352R-02specification. Bayesian method is used, In case of small actualsample volumn，It can make the prediction results have better completeness and accuracy.And recommended calculation model in this paper can accurately test RC frame interior jointshear strength.