Research On Fatigue Property Of Hollow Slab Under Carbonization Corrosion

In recent years, transportation in China has experienced a rapid development.Till the end of 2014, the country’s total highway mileage had exceeded 4.35 million km, ranked firstly in the world. As one of the basic structure forms, bridges play an important part in the building and the proper running of the road network. However,the deterioration of environment speed up the declining of bridges’ durability, affect their fatigue properties and decrease their service lives, such as carbonation, chloride ions erosion, etc,. It has aroused great attention from scholars and lead to plenty of related researches that carbonation effects on bridge durability. But most researches have been focused mainly on the influence of carbon corrosion on the concrete, and its durability affected by carbonation has not been investigated widely. In this thesis,large-sized prestressed hollow beams are made as testing targets. Through a series of durability tests, fatigue properties tests, as well as numerical simulation, the author systematically studies the effects of carbon corrosion on the durability and fatigue properties of prestressed hollow beams. The main researches content include:1. Research of manufacture and carbon corrosion test of large-sized prestressed hollow slab componentThe prestressed hollow slab models are manufactured and designed by using similarity principle. And carbonation test equipment is modified to carry out the rapid carbonization test of prestressed hollow slabs. During the experiment, the elastic modulus, compressive strength and flexural strength of the concrete are measured respectively, so as for the author to analyze how the depth of corrosion affects concrete’s mechanical properties.2. Static load damage tests on prestressed hollow hollow slab componentThe static load test of the test plate is done by using three point loading method,obtaining the ultimate bearing capacity of prestressed hollow slabs and providing basic data for fatigue test stress ratio design. And the variation law of strain,deflection and the crack extension during the static load test are summarized in thepaper.3. The experimental study on fatigue characteristics of prestressed hollow slab components subject to different degrees of carbon corrosionFatigue tests are performed on the prestressed hollow slab components that are subject to different degrees of carbon corrosion, measuring series of data such as the strain, deflection, crack extension of the slabs, and dynamic strains, dynamic displacement, dynamic frequency, dynamic damping coefficient. Through careful analysis, the effects of carbon corrosion on prestressed hollow beams’ fatigue properties are summarized. Further, a mathematical model about the relation between increasing deflections and fatigue times is built.4. Numerical simulation study on fatigue properties of prestressed hollow slab components subject to different degrees of carbon corrosionConsidering the elastic modulus, compressive strength and poisson’s ratio of concrete material with different degrees of carbon corrosion, the fatigue properties of prestressed hollow slab components subject to different degrees of carbon corrosion is analyzed by using Ansys software. By comparison with the test results, the adaptability of fatigue constitutive model for fatigue property analysis of concrete bridges subject to different degrees of carbon corrosion is analyzed.