Fatigue Cumulative Damage Detection And Fatigue Life Prediction On Reinforced Concrete Slabs

The fatigue strength of engineering structures in real life possibly can't be content with the request of code,because of the flaw in design,the questions of construction quality,the adverse influence from environment or the change of the use function(for example,the traffic density of a bridge exceeds the primitive design code).Usually,we don't allow for fatigue design when we design a reinforced concrete bridge deck slabs.As far as reinforced concrete bridge is concerned,the main reason to cause fatigue destroy is from the fatigue of bridge deck slabs,therefor how to carry out damage detection of bridge concrete slabs exactly,make sure the position and the degree of damage,predict the fatigue life and undertake corresponding reinforcement methods when necessary, is very important to the security of whole structure.The fatigue characteristics of reinforced concrete slabs are researched by the fatigue experiment of 2 slabs in this paper,and the fatigue destroy characters in normal section of reinforced concrete members are presented.The assumption of plane section can also be adopted under fatigue loading,the deformation(including strain,deflection,crack width and stiffness) of reinforced concrete member shows 3-phases rule.In this dissertation,the theory which is known of concrete structure fatigue cumulative damage and damage detection is narrated.Two methods are often used to deal with the questions of composite materials fatigue life is provided in the last part of the paper:the experience method of S-N curves and the method based on theory of fatigue cumulative damage.Furthermore,the theory of Oh concrete non-linear fatigue cumulative damage is compared with the result of experiment obtained by 3 means of calculating stiffness damage,and the proposal of predicating fatigue life of reinforced concrete member is mentioned according to the experiment.