102 / 2016-12-02 15:13:50

A In Situ Assessment Method for RC Bridges After Fatigue Damage

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In order to realize the in-situ evaluation of reinforced concrete bridges subjected to fatigue for a long time, an evaluation method for cumulative damage of concrete structures based on unloading elastic modulus is proposed. First, according to the concrete stress-strain curve and the statistical relationship between residual strain and cumulative strain, the calculation method of static equivalent strain and residual strain concrete based on unloading elastic modulus and the method for estimating the strength of concrete after damage are proposed. The detailed steps of field test and analysis and the practical damage indicators of residual strain are given. Then, the evaluation method of existing stress and strain of Reinforced Concrete Bridge under dead load and the concept of “equivalent dead load bending moment” are put forward. On this basis, the paper analyzes the root cause of the decrease of bearing capacity of Reinforced Concrete Bridge after fatigue damage, and points out that the equivalent strain or residual strain of reinforced concrete increases under the fatigue effect, which leads to the decreasing of actual live moment and deformation performance while the ultimate load-carrying capacity remains constant or very little decrease. The evaluation method of structure residual capacity is given, which has reference value for engineering practice.