FEM Analysis On The Crack Process Of Concrete Cover Induced By Rebar Non-uniform Corrosion

When the steel corrodes, the volume of rust is almost 2-4 times than the original and, thus, exerts pressure on the concrete around the rebar; as the corrosion turn worse, the cover of concrete would crack. Once the crack happened, the corrosion would be accelerated and the crack branch out even the concrete cover splitting, which results in destroy of the structures and the failure of the durability. So it has important research significance to analyze the crack process of the concrete cover due to the corrosion.Aiming at the non-uniform corrosion problem of reinforced concrete members in natural environment, the expression of radial displacement of concrete around the corner and non-corner bar is deduced by the characteristic of the rust layer. In addition, the relationship between the corrosion ratio and the radial displacement of concrete around the bar is established.The cracking process of the concrete cover due to rebar non-uniform corrosion is simulated using a finite element-based method with ABAQUS software. On the basis of the FEM analysis results by applying non-uniform radial displacement on the concrete around the bar, the distribution of the principal tensile stress is summarized and the formula of the critical radial displacement at the cracking time, which is used to predict the corrosion ratio at the cracking time of cover concrete. The analytical corrosion ratio achieves agreement with the test result well.The effect factors analysis based on FEM shows that raising the strength of concrete and the thickness of cover concrete would delay the cracking of concrete; stress superposition would appear due to the influence of adjacent rebar.