Study On The Coupled Time-dependent Effect Of Early-age Concrete Bridge

The time-dependent effects of concrete bridge, that include shrinkage, creep andtemperature effect, may lead to structural cracking and affect the structure oflong-term performance. Due to creep and shrinkage is influenced by many factors,there are not a complete consensus about the mechanism of creep and shrinkage. Andthere are some coupling effects in time-dependent effects. Now the simplifiedseparate analysis of time-dependent effects does not correspond exactly with thebridge project. Therefore, it is necessary to study the coupling time-dependent effectsof concrete bridge.The purpose of this paper: analyzing the sensitivity of the factors of concretecreep and shrinkage; time-dependent behavior of early-age concrete shrinkage straininfluenced by daily temperature changes; evolution characteristics of hydration heattemperature effect and strain of the concrete box girder; the coupling effects ofshrinkage, creep and temperature effect in early-age concrete box girder.The research was carried out under the guidance of the literature review. Theideas and methods of this study include:(1) Studying the mechanism of action and law of various influencing factors ofconcrete creep and shrinkage; the sensitivity of the factors of concrete creep andshrinkage are analyzed by principal component analysis.(2) Experiment test was carried out for the analysis of time-varying regularity ofearly age concrete strain under the influence of free air temperature changes; thestrain data and the weight of specimens were collected.(3) Analyzing the time-dependent characteristics of hydration heat temperatureeffect and strain of the concrete box girder based on field test in precast yard.(4) Selecting a suitable concrete bridge creep and shrinkage prediction model bycomprehensive analysis of impact parameter and calculation accuracy; establishingthe FEA model of constitutive relationship of coupling time-dependent effects inconcrete box girder; analyzing the coupling time-dependent effects of early-ageconcrete box girder based on the FEA model of constitutive relationship; comparative analysis of the accuracy of different models applied to coupling time-dependenteffects of early-age concrete box girder; exploring the law of influencing factorsacting on the strain of early-age concrete box girder.In this paper, the results, which are from comprehensive analysis of theoreticalanalysis and practical problems, may help to optimize the concrete bridge design,reduce the error between the design and engineering practice, help improve thequality of bridge construction and reduce bridge operation during maintenance costs.