Evaluation of Fiber Orientation in UHPC Members Using X-ray Micro-CT and Estimation of Member Strength

This study was conducted to elucidate how fiber orientation in Ultra-High-Performance Concrete (UHPC) beams affects member capacity. Beam specimens were subjected to flexural loading tests and fiber orientation observation using X-ray micro-CT, and FEM analysis was employed to reproduce the flexural capacity. The experiment was designed with placement methods and center notch presence/absence as parameters. The results indicated that specimens with fixed placement exhibited 7% more flexural capacity than with moving placement, and that the tensile stress of UHPC contributed to this. Nonlinear FEM analysis was conducted with UHPC tension-softening curves as parameters, and curves obtained from the material testing and estimated from fiber orientation were used to deduce the flexural capacity difference from the experimental results.