Study On Bearing Capacity Of Reinforced Concrete Beams Based On Corrosion

In offshore and coastal areas,steel corrosion is the main factor affecting the durability of reinforced concrete structures.Corrosion of steel bars can lead to the deterioration of the mechanical properties of the steel bars and the deterioration of working performance of reinforced concrete beams,especially serious corrosion of concrete structure can be damaged in advance.The existing researches mainly focus on reinforced concrete beams with low corrosion rate,so the evaluation of bearing capacity of reinforced concrete beams with high corrosion rate lacks of theoretical support.in order to ensure the safety of reinforced concrete beams in coastal and coastal areas,it is necessary to study the effect of corrosion on the behavior of reinforced concrete beams and to establish a reasonable durability evaluation system for concrete structures.Therefore,this paper uses the laboratory test and numerical simulation,respectively,to carry out the study of the mechanical properties of corroded steel and corroded reinforced concrete beam capacity.The main contents and results are as follows:(1)The stress-strain curve of the corroded steel bar can be divided into two types according to the yield stage of steel bars which will disappear gradually with the increase of corrosion rate.When the steel corrosion rate is small(less than 8.62%),the yield strength,ultimate strength and yield platform of the steel produce small changes,the stress-strain curve is similar to the curve of the un-corroded steel;when the steel corrosion rate is 12.6%,the yield stage of the corroded steel completely disappears,and the relationship between stress and strain has no yield platform.(2)The nominal ultimate strength and the nominal yield strength of the corroded steel exhibit a good linear degeneration rule with the increase of corrosion rate.Relative to the nominal yield strength of the steel,the nominal ultimate strength is more affected by the rate of corrosion,and the degradation rate is faster.The ultimate elongation also showed a good linear relationship,but the anisotropic corrosion of the reinforcement results lead a relatively large dispersion of the ultimate elongation.(3)The corrosion can cause the change of the failure characteristics of reinforced concrete beams.When the corrosion rate is less than 5%,the steel bar corrosion does not change the failure characteristics of reinforced concrete beams;when the corrosion rate of steel bar is more than 10%,the reinforced concrete beam changes from the tendon damage to the less tendon failure.The corrosion does not affect the cracking moment of reinforced concrete beams,but the corrosion will decrease the bearing capacity of reinforced concrete beams,especially when the corrosion rate is 25%,the bearing capacity of the reinforced concrete beams decreases to 22.23%.It is suggest that the reinforced concrete beam should be reinforced when it is severely corroded.(4)The bearing capacity of corroded reinforced concrete beams of different reinforcement ratios will decrease with the increase of corrosion rate.Under the condition of the same corrosion rate,the large diameter of the steel is beneficial to resist the influence of corrosion on the bearing capacity of reinforced concrete beams.When the bearing capacity is satisfied,it is suggested that properly increasement of the reinforcement ratio can prevent the premature failure of the beam caused by corrosion of steel bars.