Flexural behaviour of normal concrete circular beams strengthened with ECC and stainless steel tubes

The use of laminated fibres for strengthening reinforced concrete beams is challenging owing to bonding and compatibility issues, especially in scenarios where cost effectiveness and long-term performance are important. A novel flexural strengthening technique for normal concrete circular beams (NCCBs) is proposed, using engineered cementitious composites (ECCs) and stainless steel tubes (SSTs). To examine the application of the proposed strengthening method, five NCCBs were fabricated and tested under static loading until failure to investigate the effects of ECC thickness and SST thickness. The test results showed that the strengthening technique greatly improved the failure pattern and the ultimate flexural capacity of the tested NCCBs, and the enhancement increased with an increase in the thickness of the ECC and SST. Using Abaqus software, finite-element models were constructed to simulate the performance of the tested NCCBs. The accuracy of the finite-element modelling was confirmed by comparing the simulations with the experimental results. The validated model was used for a detailed parametric investigation of the effects of the thickness of the ECC and SST on the failure and ultimate bending capacity of the strengthened beams.