Effective restoration of reinforced concrete beams with severe stirrup corrosion using high-strength strain-hardening cementitious composites (SHCC)

The corrosion of steel in reinforced concrete (RC) beams is a significant problem that can lead to premature structural failure. Specifically, shear stirrups with less concrete cover than flexural reinforcements are more vulnerable to early corrosion. Traditional repair techniques by attaching additional reinforcements to the corroded stirrups through lapping are time-consuming and costly. Moreover, achieving adequate lap length for effective stress transfer may not be feasible if the depth of the beam is limited. To solve the above issue, this study introduces an innovative repair technique using high-strength Strain-Hardening Cementitious Composite (SHCC). This material can sustain significant tensile/shear stress at elevated strain levels and then eliminate the need for stirrup lapping and extensive concrete removal. Four-point bending tests were performed on RC beams with a region (covering some adjacent stirrups) with a high percentage of stirrup area loss to simulate the severe situations, with and without a high-strength SHCC patch. Test results showed that the high-strength SHCC patch can effectively restore the ultimate load-bearing capacities to 96.12 % and 98.90 % of the full capacity of uncorroded beams for 50 % and 100 % stirrup losses, respectively. Finite element models were developed to simulate the behavior of both the reference and patched beams, and the numerical predictions satisfactorily matches the experimental outcomes. These findings demonstrate the effectiveness of using high-strength SHCC patch to restore the load-bearing capacity of RC beams with severe stirrup corrosion, thereby validating the practical applicability of this innovative repair technique. • High-strength SHCC was explored to repair reinforced concrete beams with severe stirrup corrosion. • Required properties of repair material (SHCC) were determined according to the rough geometry of the patch. • The load-carrying capacity of beams with reduced stirrup areas can be recovered > 95 % with a high-strength SHCC patch. • Finite element simulations were in satisfactory agreement with the experimental results. • The proposed repair technique is more efficient and less time-consuming than the conventional technique.