Shear Performance of RC Beams Strengthened with Steel Strand Wire Mesh–Reinforced Engineered Cementitious Composites under Cyclic Loading

Abstract

A steel strand wire mesh (SSWM)–reinforced engineered cementitious composite (ECC), referred to as SSWM-ECC, is a promising composite material for structural strengthening owing to the combination of the high strength of SSWM and the high ductility of ECC. This paper presents an application of SSWM-ECC for shear strengthening of reinforced concrete (RC) beams subjected to cyclic loading. First, cyclic loading tests were conducted on two control beams and five strengthened beams, considering various shear span-to-effective depth ratios, reinforcement ratios of the SSWM, and strengthening schemes. The test results showed that brittle failure and degradation of the shear properties of the strengthened beams were effectively mitigated. Compared to the control beams, the ultimate load, cracking load, service load, ductility, and energy absorption of the strengthened beams increased by 18%–40%, 145%–208%, 35%–126%, 20%–65%, and 58%–96%, respectively. The improvement in shear performance increased with increasing reinforcement ratio of the SSWM and shear span-to-effective depth ratio. In addition, the fully wrapped strengthening method effectively confined the concrete, resulting in a more significant increase in the shear performance of the beams compared to the U-wrapped and both-sided methods. Furthermore, a modified truss arch model was developed to predict the shear strength of the strengthened beams. The results predicted by the proposed model exhibited greater accuracy than those generated by various existing models, including those commonly utilized in the field. The experimental study presented in this paper demonstrates a significant improvement in the shear performance of RC beams subjected to cyclic loading using a novel composite called SSWM-ECC. This method is expected to be useful for structural strengthening. The fully wrapped, U-wrapped, and both-sided SSWM-ECC strengthening methods introduced in this paper are applicable to a wide range of engineering projects. In particular, an economical and convenient method for strengthening RC beams using externally bonded prefabricated SSWM-ECC plates is presented. The SSWM-ECC can effectively mitigate the shear brittleness of RC beams subjected to cyclic loading and significantly increase their shear strength, stiffness, cracking resistance, energy absorption, and ductility. Furthermore, the strengthening efficiency increased with increasing shear span-to-effective depth ratio and reinforcement ratio of the SSWM. Finally, a calculation method for predicting the shear strength of strengthened beams is proposed, which provides a basis for the design and application of shear strengthening of RC beams with SSWM-ECC under cyclic loading.