Preliminary Study On The Concrete Cover Corrosion-Induced Cracking By The Application Of Smeared Cracking Model

Finite Element Analysis based on smeared crack model on concrete cover crackingcaused by corrosion-expansion is used. An analysis model is proposed to calculate thesteel corrosion ratio and the critical corrosion-expansion pressure. The main work andconclusion of this paper are:1、The experiment of concrete cover cracking caused by steel corrosion have beenmade. This paper obtains two groups corroded specimens with different diameters（c/d=4.5、d=12m m、18mm） and different corrosion percentage. Then the distributionof the corrosion expansive cracks is inspected by using the non-destructive IndustrialComputed Tomography （ICT）. Before concrete cover cracks appeared, the corrosionratio is very small and the internal crack is difficult to find. But the steel will rapidlycorrosion once the cover cracks appeared. Corrosion product is filled into the internalcracks along the crack path and the external crack extension.2、Quasi-static analysis in ABAQUS based on smeared crack model is used tosimulate concrete cover cracking caused by general corrosion of steel. Reasonably goodagreement between experimental phenomenon and the analytical predictions has beenobtained. It has also been found that coarse aggregate size and concrete gradesignificantly influence on concrete cover cracking extension.3、This thesis proposes a model by analyzing an equivalent thick-wall cylindersubject to a uniform internal pressure. To describe the behavior of concrete in thesoftening region, a constant stress field are assumed. Mathematical expressions wasfound to calculate the critical corrosion-expansion pressurePc rin the state of stress. Todetermine the validity of these models, their results are compared to publishedexperimental data. Finally, a parametric analysis using the models is carried out in orderto find the effects caused by model parameters，such as bar diameter （d）, concrete coverthickness（c）, concrete material strength on the critical corrosion-expansion pressurePcrAnalysis results show that the corrosion-expansion pressurePc ris almost linear increaserelationship between the tensile strength of concrete and c/d.4、An analysis model is proposed to calculate the critical corrosion ratio(η_cr)whenthe concrete cover begin cracking, which was found by the existing relationshipbetween η_crandP_cr.This provides an analysis method to obtain the amount of steelcorrosion ratio. The applicability of this analytical model was provided on experimental research, which verified the rationality of the analytical model. The effects caused bytensile strength of concrete（f_t）、effective modulus of elasticity of concrete(E_ef)、bar diameter（d）, concrete cover thickness（c）, ratio of volume of expansive corrosionproducts to the volume（n）、poisson ratio on crhave been discussed. Analysis resultsshow that the steel corrosion ratio cris sensitive to c/d、n,but limited effects by otherfactors...