Experimental results and modelling of corrosion-damaged concrete beams strengthened with externally-bonded composites

This paper presents the results of 3D finite element (FE) modelling of corrosion-damaged reinforced concrete (RC) beams strengthened in flexure with externally-bonded composites. The models were validated against the results of experimental tests conducted on ten unstrengthened and strengthened beams. The investigated parameters included the corrosion levels (10 and 20% mass loss of steel reinforcement), the type of composite (fabric-reinforced cementitious matrix (FRCM) and fiber-reinforced polymers (FRP)), and the number of composite layers (one, two, and four). The predicted results showed good agreement with those of the experimental tests. The FE models were able to capture the non-linear behavior of the strengthened beams. The interfacial bond stress-slip models at the fabric/matrix and composite/concrete interfaces and the number of composite layers had the most significant impact on the predicted response of the strengthened beams whereas the corrosion level, modeled as a reduction in the steel reinforcement cross-section, showed a slight effect on their performance. The validated models were used in a parametric study to investigate the effect of varying the compressive strength of the concrete substrate and the thickness of concrete cover on the flexural performance of the strengthened beams. It was observed that lowering the concrete compressive strength or increasing the concrete cover decreased the load-carrying capacities of the strengthened beams regardless of the strengthening system used (FRCM or FRP). Unlike the FRP-strengthened beams, the failure of FRCM-strengthened beams was independent of both parameters and was solely governed by the fabric slippage within the matrix.