Investigating Pullout Behavior of Inclined Superelastic SMA Fiber in a Mortar Matrix Based on Finite Element Method

The advanced FE pullout model, incorporating superelasticity of SE-SMA fiber, concrete plasticity, shrinkage effects, and contact surface parameters, explores the impact of inclined angles on pullout responses, subsequently elucidating the pullout mechanism. Longitudinal and cross-sectional stress distributions of SE-SMA fibers (0.5 mm and 1.0 mm diameter) during pullout are examined, revealing noteworthy conclusions: pullout is constrained within a 9° inclined angle, leading to fracture beyond this threshold; the inclined fiber's pullout response manifests two peak stresses arising from pulling and bending effects, with the first stress being angle-independent and the second increasing linearly with the angle; the first peak stress remains constant in the embedded portion but varies in the free portion due to bending, while the second peak stress varies in the embedded portion, particularly on the side of larger eccentricity; thin fibers exhibit higher first and second peak stresses compared to thicker counterparts, with the second peak stress displaying greater scatter in the cross section, making thin fibers more susceptible to fracture during pullout. These findings contribute to future pullout experiments and enhance understanding of SMA fiber behavior in reinforced concrete composites.