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11Corrosion-induced concrete cracking is a significant durability problem for reinforced 12 concrete structures. Considerable research has been carried out in the last few decades to 13 understand and model the expansion mechanism of the corrosion products around the 14 reinforcing bar and simulate the cracking behaviour of the concrete cover. In this paper, a 15 new corrosion model based on non-uniform corrosion expansion is formulated and validated 16 against experimental data. A meso-scale fracture model, consisting of aggregates, cement 17 paste/mortar and ITZ, is established for the cases of both middle and side reinforcing bars. 18Under the developed corrosion and concrete fracture model, the cracking phenomena of the 19 concrete cover are accurately simulated. It has been found that the non-uniform corrosion 20 model can be used to express the realistic corrosion rust progression around the reinforcing 21 bar, with the best accuracy. It has also been found that some microcracks occur before they 22 are connected to form the dominating discrete crack which usually appears on the concrete 23 surface. Moreover, the effects of the corrosion variables, as well as other key material and 24 geometric parameters, on surface cracking of concrete are investigated. 25 Keywords: non-uniform corrosion, cohesive crack model, meso-scale, reinforced concrete 26 structures, finite element method. 27 * Corresponding author. Tel: +44 141 548 3273. Email: shangtong.yang@strath.ac.uk. 28 reduction. Li et al. [8] developed an analytical model to calculate the crack width of concrete 48 cover by assuming the cracks smeared in concrete and considering concrete as a quasi-brittle 49 material. Among these existing studies, most are focused on uniform or general corrosion of 50 the reinforcement. 51 52Chlorides, as well as moisture and oxygen, diffuse into concrete and reach a threshold value 53 at the surface of steel bar, before the passive layer on steel surface is destroyed and corrosion 54 is initiated [9]. However, it is rare to have a uniform corrosion around the reinforcing bar, due 55 to different amount of chlorides, moisture and oxygen that are available on different sides of 56 the reinforcement; for example, the side of a reinforcing bar facing concrete cover should 57 have more sources to advance corrosion and hence more corrosion products accumulated on 58 this side. Recently, many researchers have started to model the cracking of concrete cover 59 induced by non-uniform corrosion of reinforcement. González et al. [10] perhaps first 60 compared the depth of pitting corrosion penetration on steel bar with the depth of general 61 corrosion and found that the maximum penetration of pitting corrosion on the steel bar is 62 equivalent to about three to sixteen times of the penetration of general corrosion. Jang and Oh 63 [11] extended the experimental results in [10] and designed a factor for the ratio of the 64 maximum thickness of non-uniform corrosion layer to the thickness of uniform corrosion 65 layer to express the n...

TABLE OF CONTENTS vi LIST OF FIGURES xi LIST OF TABLES xvi NOTATION xvii CHAPTER 1 INTRODUCTION 1.1 Background xix c f Concrete strength in compression ,0 c f Strength of zero porosity ' t