Analysis Of Corrosion-induced Expansive Cracking Of Concrete Cover Based On Micro-plane Theory

When the rebar corrodes, the volume of corrosion products is almost 2-4 times that the original steel. The corroded rebar exerts an expansive pressure on the concrete around the rebar. As the corrosion propagates, the concrete cover will be cracked owing to insufficient tensile strength. Once the concrete member is cracked, the corrosion will be accelerated and the crack will propagate further, which results in structure failure and influences the durability of the structure. Therefore, it is of great practical significance to study the corrosion-induced cracking process of the concrete cover.Based on the current research, the main work of this thesis includes the followings:(1) The constitutive model of concrete is studied based on the micro-plane theory and a nonlinear finite element program for the analysis of concrete structures is developed. By comparing with the experimental results of a beam, the validity of the program is verified.(2) For the uniform corrosion of the rebar, the various factors that affect corrosion-induced cracking process are analyzed. Based on the numerical results, it is found that the service life of concrete structures increases effectively with the increase of the tensile strength of concrete, cover depth, rebar diameter, and rebar spacing but with the decrease of the corrosion current density.(3) Based on the results of the finite element analysis, the various factors that affect the failure pattern of the cover are analyzed. It is found that, for a given cover depth and rebar spacing, the rebar diameter has little influence on the failure pattern of the cover. For a given cover depth and the rebar diameter, the failure pattern is changed from whole spalling to longitudinal cracking by increasing the rebar spacing. For a given rebar spacing and rebar diameter, the failure pattern is changed from longitudinal cracking to whole spalling by increasing the cover depth.