Flexural behavior of RC beams strengthened with BFRP bars-reinforced ECC matrix

This paper has proposed a new strengthening system made of basalt fiber-reinforced polymer (BFRP) bars-reinforced engineered cementitious composite (ECC) matrix (hereinafter referred to as BFREM for brevity) for repairing of RC beams. Six specimens including a control beam and five beams strengthened with the BFREM layers were prepared and tested. The test variables included the reinforcement ratio of BFRP bars (0.94% or 1.41%) and the installation method (prefabricated or cast-in-place) used for the BFREM layer as well as the presence of the end anchorage system (with steel bolts). The test results showed that two failure modes of the strengthened beams were the tensile rupture of BFRP bars and the concrete cover separation with the strengthening layer attached. The cast-in-place method incorporating the end anchorage system was capable of inhibiting the debonding failure of the BFREM layer, thereby making better utilization of the strengthening materials. Moreover, the proposed strengthening system was efficient in enhancing the ultimate loads of the strengthened beams, which were 34%-48% higher than that of the control beam. A theoretical analysis was then conducted to predict the flexural strengths of the tested beams, and its reliability was verified by comparing the test results and the theoretical predictions.