Research On Performance Degradation Model Of Corroded Reinforced Concrete Beams

Reinforcing bar corrosion is one of the most important factors which deteriorate durability of concrete structures and members. The reinforcing bars in concrete structures are prone to corrosion under aggressive environments attack, which causes degradation of mechanical properties of structural materials such as concrete and rebar, also leads to weakness of bond performance between concrete and surrounding reinforcement together with decrease of dimension of corroded concrete members. Therefore, the corrosion of reinforcing bar greatly threatens the safety of concrete structures. The performance degradation model research of corroded reinforced concrete beams plays a prominent role in the study of reinforced concrete beam which is an important component in the concrete structure.This paper mainly studied the flexural bearing capacity of normal section of the corroded reinforced concrete beam, the shear bearing capacity of inclined section and the effective bending stiffness of corroded beam, and analysis the seismic damage of corroded reinforced concrete beams based on ABAQUS, simulated the destruction of concrete under complex stress condition using the plastic damage model of ABAQUS program.The article studies the mechanical properties of the steel after corrosion and corrosion morphology through immersion tests which soaked the steel in acid rain solution (PH=4.8) and sodium chloride solution (3.5 wt%) for 3 days and 8 days. The results showed that corrosion product generated in the surface of the steel bar both in chloride solution and simulated acid rain solution, the corrosion product in chloride solution was tighter than that in simulated acid rain solution, steel corrosion in simulated acid rain solution was more serious than that of chloride solution, mass lose of steel bar increased with the soaking time, under the condition of low corrosion rate, the yield strength and ultimate strength of steel bar was almost unchanged.This paper select lower corrosion rates reinforced concrete beams as research object, a calculation formula of flexural baring capacity of corroded reinforced concrete beams was put forward based on the plane section assumption. Furthermore, a theoretical expression of equivalent stiffness of corroded reinforced concrete beam was suggested by using transformed section approach. The weakening of the bond between concrete and reinforcement was considered in this method. In addition, a theoretical formula of mid-span deflection of corroded reinforced concrete simply supported beams subjected to a four-point bending was proposed. The analytical model was verified using 39 corroded reinforced concrete beams. The trend between test load-mid span deflection curves and predicted curves is much the same. Thus, the suggested model can be served as a reference for full-range analysis of corroded reinforced concrete beams.Combining with the existing test results, the shear bearing capacity of corroded reinforced concrete beams is discussed basing on the experimental study. By selecting corroded reinforced simply supported concrete beams as research object, a analysis model of shear baring capacity of corroded reinforced concrete beams under concentrated loads was put forward based on the experimental investigation of shear behavior of corroded reinforced concrete beams, particularly the shear strength of corroded beam was calculated by using strut-and-tie model. The suggested analytical model was verified using 75 corroded reinforced concrete beams.By analyzing the seismic damage of twelve corroded RC beams, the curve of seismic damage index changing with load cycle levels is obtained, namely D-N curve. The seismic damage evolution of corroded beams and the influence of corrosion ratio, specimen failure mode on seismic damage index are analyzed. The analysis shows that:seismic damage index of corroded RC beam increases with the increase of cycle levels, and the growth rate is gradually increased; the displacement amplitude of cyclic loading specimen experienced plays an important role in the seismic damage model of corroded beam.