A new model for calculating inclined single fiber bridging stress in Strain-Hardening Cementitious Composites based on beam theory

Abstract

A new model for calculating the bridging stress of inclined fiber is developed in this paper. While the full debonding/pullout behavior can be derived from the model, particular focus is placed on the situation with small crack opening, which is the operating condition for Strain- Hardening Cementitious Composites (SHCC). The model reveals the physical mechanism of the ‘snubbing effect’ for fiber with bending stiffness, i.e. even without the assumption of a frictional pulley, the ‘snubbing effect’ can arise from the increasing bending force component due to the ‘P-δ’ effect of the axial force. Parametric study is performed in order to study the effects of different parameters on the ‘snubbing effect’. Shear deflection of the fiber is also studied and is found to be unimportant compared to the bending effect. Matrix spalling is incorporated into the model and its effect is discussed. Single fiber pullout tests have been conducted to verify the model directly, and good agreement was found between the model prediction and experimental results. In addition, the new model is computationally efficient and hence has good potential for practical application in the micromechanics-based design of SHCC.