Analysis Of Shearing Mechanism And Bearing Capacity Of RC Beams After Corrosion

Reinforced concrete structure is widely used in major civil engineering and facilities,and its durability research is a long-term hot issue in the field of engineering.China has the most bridges in the world,and most of them are reinforced concrete beams.With the increase in service life,huge maintenance pressure has brought serious challenges.During service,due to poor service environment,design reference period,design defects and other reasons,the cross-sectional area of the steel bar inside the structural member is reduced,the mechanical properties of the steel bar are degraded,the bonding performance between the steel bar and the concrete is changed,and the rust expansion product causes the internal occurrence of the concrete damage.These factors directly or indirectly weaken the performance of reinforced concrete structural members,and even bring huge hidden dangers to the overall safety of the structure.At the same time,corrosion may change the competition mechanism of shear and bending failure of reinforced concrete beams,causing brittle failure of the beams and causing serious damage to the structure.Therefore,it is necessary to establish a reasonable and effective analysis method to evaluate the remaining performance of the corroded reinforced concrete beam.This article combines finite element simulation analysis and theoretical analysis for research.The main research contents are as follows:(1)Based on the finite element analysis software ABAQUS,this paper proposes a simulation method of stirrup corroded concrete beams.In this method,the change of the bond properties between the stirrup and the concrete after corrosion is considered,and the influence of the stirrup on the bond properties of the main reinforcement after corrosion is also considered.The simulation analysis results are compared with the test results to verify the reliability and effectiveness of the simulation method,which provides a basis for further analysis and evaluation of the remaining shear performance of the corroded beam.(2)Based on the simulation analysis method of the stirrup corrosion RC beam proposed in this paper,the enlarged parameter analysis is carried out.The analysis considers the two variables of stirrup corrosion rate and concrete strength,discusses the shearing performance of each group of reinforced concrete beams,systematically analyzes the bearing capacity,stiffness,relative slippage and failure mechanism of reinforced concrete beams,Provide reference and basis for future numerical simulation analysis and experimental research.(3)Based on the existing calculation model of shear capacity of RC beams,from the perspective of engineering application and theoretical analysis,the prediction formula of remaining shear capacity of RC beams considering corrosion is proposed,and their respective characteristics and scope of application are analyzed.The practical calculation model mainly considers the influence of the main reinforcement corrosion on the shear bearing capacity.Through a large number of test data statistics,the shear strength reduction formula of the corrosion-free beam without web reinforcement is proposed.Based on this,combining the Chinese concrete structure design code,the American concrete structure design code,and the uncorroded RC beam shear strength calculation formula proposed by the Chinese Academy of Building Research,the RC beam with corroded shear strength calculation formula is proposed.The calculation results of the three formulas are compared with the existing 86 sets of test data,and the characteristics and application scope of each formula are analyzed.In terms of theoretical analysis,based on the truss-arch model,the material degradation caused by the corrosion of stirrups is considered,the concrete in the core area is "softened",and the effective cross-sectional width is reduced.A theoretical calculation model is proposed.Compare the calculation results of the model with the test results and discuss the characteristics of the analysis model.