Prediction Of Fatigue Damage And Life Expectancy Of Concrete Bridges With Reinforcement Corrosion In Overloading Of Heavy Vehicle

In previous research of reinforced-concrete structure or member,the method of fatigue test has become the main approach to research the fatigue issues at home and abroad.With the development and optimization of finite element software,the numerical simulation method was gradually adopted by researchers,due to its low cost and superior repeatability.Both numerical simulation and test complement each other during the research on reinforced concrete fatigue.Fatigue test lays the foundation of fatigue numerical simulation.For instance,initial material mechanical parameters and corresponding degradation models during the fatigue numerical simulation of reinforced concrete are obtained by fatigue test.For the fatigue test with high cost and long test period,accurate numerical simulation can be employed to make up the drawbacks.That is,fatigue properties of reinforced concrete structure,as well as entire fatigue loading process can be simulated and researched,based on several fatigue tests.However,there are many problems in numerical simulation process.For example,during the fatigue loading process of reinforced concrete structures or members,different degradation model of mechanical parameters and different constitutive relations lead to different models.It needs to be solved to make numerical simulation more accurate and more applicable in reasonable manner.Thus,the research was carried out in accordance with the progressive way,namely constituent materials,reinforced concrete members,and reinforced concrete bridge structure.The main work of this study are as follows:1.Based on the results of existing research on fatigue of concrete,various degradation model of mechanical parameters and constitutive relation are discussed and analyzed.S-N curve equations of concrete fatigue are established according to maximum stress level.2.Based on the results of existing research on fatigue of reinforcement,various degradation model of mechanical parameters and constitutive relation are discussed and analyzed.Both the degradation models of fatigue residual strength,and common S-N curve equation of steel fatigue are established.3.Based on data of multiple sample test,various parameter degradation models of fatigue properties are optimized and analyzed.And finite element numerical reference models of fatigue properties of structure are established,including static load reference model and fatigue benchmark model.The degradation law of fatigue performance of structure and member is probed on the basis of model test and relevant test data.The prediction model of various parameters are established,including mid-span deflection,concrete strain,reinforcement strain and residual ultimate bearing capacity.Accordingly,the deflection,strain and residual capacity limit under the action of fatigue load explored.And more accurate prediction method of remaining service life is prospered.4.Based on the establishment method of reference model,the finite element analysis model of Beijing-Miyun Highway Baihe Bridge is established.Based on the survey data of heavy vehicle load and time-varying regularity of traffic volume,the fatigue properties under overload,steel corrosion and fatigue are studied during bridge service life.The life expectancy is predicted.