Experimental Study On Fatigue Behavior Of The Damaged Reinforced Concrete Beam

Concrete structure has been widely used in these structure, such as Bridges, roads, crane beam, ports. Dynamic loading leads to fatigue problems in the process of using. At the same time, the material and structural performance deterioration under the effect of long-term environmental factors will lead to further reduce of structure fatigue life.This thesis is based on an key project of National Natural Science Foundation (Joint Found No.1361204) named "More than30tons and axle load condition of railway infrastructure dynamics characteristic and adaptability", using the longitudinal reinforcement corrosion and concrete carbonation as variables. The objective of the research is to fatigue out how the longitudinal reinforcement corrosion rate and concrete carbonation are affecting the fatigue behavior of the corroded R.C. beams. The content and the conclusion of the paper are as follows:(l)Use the concrete carbonation and steel corrosion that caused by environmental factors as the variables, a fatigue load test is conducted in9Reinforced concrete beam with different corrosion rate and carbonation depth. The concrete carbonization depth and steel bar corrosion rate of specimen that get form Rapid test is close to design value. The result proves that the fatigue test and test method are successful.(2) Studying the influence of corrosion rate on the fatigue life and damage evolution law. Test shows that:with the increase of longitudinal reinforcement corrosion rate, the fatigue life decrease significantly, failure pattern by reinforced crush fracture into concrete crush, Beam stiffness decreased obviously, the crack width increases and the number decrease.(3) Studying the influence rule of concrete carbonization on beam fatigue life and damage evolution law by the test. The test shows that: concrete carbonization has little influence on beam fatigue life, cross section stiffness and the fracture development.(4) According to the test results in this paper, and the test data of domestic and foreign existing corroded reinforced concrete beam, fitting out the beam fatigue life S-N curve prediction model that consider rebar corrosion rate.(5) According to the three-stage development law of the residual strain of the concrete and based on the analysis of concrete fatigue damage development law, a fatigue accumulative damage equal using the residual strain as the damaged variables is built to predict the remaining fatigue life of different longitudinal reinforcement corrosion rate corroded R.C. beams.