ABSTRACT
In this contribution, a model-based investigation is conducted to correlate fiber orientation measures with the post-cracking strength of Fiber-Reinforced Concrete (FRC), thereby providing guidance for the engineering design of FRC structures. For this, a multi-level model for the analysis of FRC structures is used, which allows to assess the influence of a chosen fibre type, content, and orientation on the structural response. Using data from segmented CT images, the effects of the fiber orientation, fiber content and embedment length on the fiber bridging stress are quantified. After providing an overview of models describing the fiber orientation state and their relation to experimental measurements, the model is validated by the re-analysis of 3-point bending tests, using the fiber orientation state from segmented CT images as explicit model input. Additionally, assumption-based predictions using different orientation tensors are carried out to discuss the influence of incomplete information. A parametric study quantifies the discrepancy between post-cracking strengths obtained from standard FRC characterization tests and the post-cracking strength expected in the to-be-designed structural member due to differences in fiber orientation. The results demonstrate how the fiber orientation state governs the post-cracking performance and provide practical guidance for incorporating orientation effects in the design of FRC structures.
