Three-dimensional modelling of structural effects of corroding steel reinforcement in concrete

Artikel i vetenskaplig tidskrift, 2013

The effect of corrosion products flowing through cracks becomes significant when large corrosion penetrations take place in reinforced concrete structures and wide cracks develop; this is favorable, as it decreases the splitting stress around the bar. The effect becomes more important when the corrosion rate is low, such as for natural corrosion. A corrosion model describing the expansion due to voluminous corrosive products was previously developed. The model is here extended to include the flow of corrosion products through cracks. The volume flow of corrosion products through a crack is assumed to depend on the splitting stress and the crack width. The splitting stress is evaluated from the strain in the corrosion products, and the crack width is computed from the displacements across the crack. A one-dimensional flow model is used to formulate the flow phenomenon and to estimate the volume flow of corrosion products. The extended corrosion model, applied in detailed three-dimensional non-linear finite element analyses of highly corroded eccentric pull-out specimens, resulted in more corrosion cracks with smaller crack openings, which better corresponded to measurements of the tested specimens. Moreover, the results indicated the important effect of the flow phenomenon on the bond strength.