Research On Calculation Method Of Bearing Capacity Of Corroded RC Compression-bending Members With Large Eccentricity

Corrosion will weaken the bond strength between reinforcement and concrete.Under external load,bond degradation will cause slippage between reinforcement and concrete,and then affect the cooperative working ability between them,resulting in uncoordinated deformation.The traditional plane section assumption is not applicable to corroded members with slippage.Therefore,this paper has done the following theoretical research and analysis,and based on the intelligent algorithm,explore the probability model of the computational model.The slip mechanism between corroded reinforcement and concrete is analyzed,and a new theoretical model is established to investigate the interface slip deformation and mechanical behavior characteristics of corroded reinforced concrete flexural members with large eccentricity.Based on the sliding principle of steel-concrete composite structure,the nonlinear analysis of large eccentric bending member is carried out considering the influence of corrosion and external load.By introducing the constitutive relation of bond slip between concrete and corroded reinforcement,the equilibrium relation of internal forces,the differential relation of axial force and slip amount,the deformation coordination relation and slip boundary conditions,the co-working coefficient and the analytical equation of slip amount are given to characterize the slip effect.The distribution and influencing factors of co-working coefficient and slip quantity are described quantitatively,and some engineering suggestions on how to control the spread of bond slip damage are put forward.Furthermore,a calculation method for the bearing capacity of the corroded bending member with large eccentric pressure considering the slip effect was established.The calculation results were verified by the experimental results of 22 corroded bending members with large eccentric pressure.The comparison results show that the calculated values are in good agreement with the experimental values.The influence of concrete strength,crack width and steel yield strength on ultimate bearing capacity,it can be seen that the underutilization of steel yield strength is one of the main factors causing the reduction of bearing capacity of corroded eccentric bending members.Based on the established slip-mechanical behavior characteristic model,the effect of nonuniform corrosion on the bearing capacity of the bending member was further analyzed.What’s more,the calculation model of the bearing capacity of the bending member with non-uniform rust and asymmetric corrosion was derived.The theoretical results were compared with the experimental data and the calculation results of the two-step method,which verified the rationality and applicability of the calculation model.In the research and analysis of the above two models,it is found that the accuracy of the mechanical model is affected by the uncertainty parameters.The values of the existing uncertainty parameters are mostly based on experimental studies,and there is no uniform value result.Therefore,this paper further studies the MCMC intelligent algorithm,which is mainly based on Bayesian estimation to obtain the posterior distribution of the uncertainty parameters.The prior distribution and sample information were combined to predict the parameters,and the probability model was finally obtained.The accuracy of the model was verified by comparing the experimental data with the traditional theoretical calculation results.