Study on Flexural and Fatigue Behavior of SMA-CFRP Composite Strengthened Notched Steel Beams

Carbon fiber reinforced polymer (CFRP) can significantly improve the bearing capacity of damaged structures. To efficiently impede the existing cracks, a prestressed CFRP strengthening method was proposed. But this method was limited by the requirement of additional mechanical devices. Heating the pre-deformed shape memory alloy (SMA) in the constrained state, SMA can provide prestressing, thereby providing an alternative of the prestressing method. Combining SMA and CFRP for steel strengthening can integrate the advantages of the two materials and even obtain a better strengthening effect. This paper conducted an experimental study on the flexural and fatigue behavior of notched steel beams strengthened by SMA (NiTiNb)-CFRP composite. The bearing capacity, failure mode, strain at the notch tip, and fatigue life were analyzed. The results showed that SMA-CFRP strengthening can significantly improve the bearing capacity and fatigue performance of the notched steel beams. The SMA-CFRP strengthening method provided a much higher strengthening effect than using a single material. Moreover, SMA-CFRP strengthening can further improve the yield load at the notch tip, thereby better inhibiting the crack development.