Experimental investigation of flexural properties of engineered cementitious composites reinforced with superelastic shape memory alloy fibers under cyclic loading

To further enhance the flexural performance and self-centering capacity of engineered cementitious composites (ECC) under dynamic loading and harsh environmental conditions, this study introduces superelastic shape memory alloy (SMA) fibers into PVA-ECC, resulting in hybrid fiber-reinforced cementitious composites (SMAFECC). The mechanical properties of SMAF-ECC thin plates under cyclic four-point bending tests were systematically investigated. Using digital image correlation (DIC) technology, the effects of SMAF content, diameter, and shape on mid-span deflection, self-centering capacity, energy dissipation, cyclic modulus, and equivalent viscous damping coefficient were analyzed. The results indicate that SMAF with a content of 0.5 %, diameter of 0.7 mm, and flat-headed shape exhibited the best overall performance. As the SMAF content and diameter increased, the cyclic modulus of the specimens significantly improved, while residual deflection decreased by 61.9 %. The self-centering factor r increased to 0.85, representing a 30.8 % improvement over conventional ECC. Energy dissipation capacity increased by 20 %-50 %, but declined after the maximum deflection. Simultaneously, the equivalent viscous damping coefficient increased by 5.6 %-11.1 % in the later stages. These findings provide a theoretical foundation for the application and optimized design of SMAF-ECC materials.