Deterioration Of The Reinforced Concrete Beam Under The Chloride Coupled With Load

Sufficient attention has been paid to the durability of reinforced concrete structures widespread all over the world. The chloride diffusion in the reinforced concrete structures under marine conditions will cause the corrosion of steel bars and durability degradation of concrete, finally, failure of the structures. This research focuses on the time-dependent properties of reinforced concrete under coupled environment and load conditions. And the main contents of this investigation include:(1) The influence of defect surface state and defect degree of corroded steel bars on the ultimate strength was simulated using the FEM method. The simulation research proves that the corrosion morphology of steel bars is the key factor to affect the strength of steel bars. Based on the simulation of single corrosion pit, the mechanical properties of steel bar with two corrosion pits are studied.(2)When the steel bars are corroded, the expanding rust would apply extra forces on the concrete around the steel bars. As the corrosion turns worse, the cover of concrete would finally crack. In order to determine the corrosion ratio when the concrete starts to crack, concrete specimens were subjected to two different accelerated corrosion conditions. During the test, the width of the crack was monitored to determine the cracking time of reinforced concrete. Based on the shape of the rust, a model was put forward to predict the corrosion ratio when the concrete began to crack. And a new method was designed to investigate the corrode cracking of reinforced concrete under different loading level. The affecting factors of loading on the corrode cracking was discussed.(3) The time-dependent performance of corroded concrete beams under coupled environment and loading conditions was studied with two accelerated corrosion methods, the artificial climate method and the galvanization methods. The experiment results show that the corrosion characteristics and behaviors of steel bars corroded in galvanization methods and artificial climate method are clearly different. The bearing capacity and ductility of reinforced concrete beams decrease and the cracks distribute more sparsely and nonuniformly with the increase of corrosion rate. Under coupled continues loading and accelerated corrosion conditions, the deflection of reinforced concrete beams increases with the progressive corrosion of reinforcement.