Fiber Distribution and Alignment in Structural UHPC Elements скачать в хорошем качестве

Fiber Distribution and Alignment in Structural UHPC Elements

Presented By: Le Pham, Wiss Janney Elstner Associates, Inc Variations in the quantity and orientation of steel fibers at critical locations within a structural ultra-high performance concrete (UHPC) element can impact its ability to carry and distribute tensile stresses. Since UHPC is typically placed as a highly flowable material, the fibers in UHPC tend to align along the direction of flow and, in undesirable conditions, may segregate. Depending on the application, both unfavorable fiber alignment and segregation can negatively affect the tensile behavior of the UHPC. Thus, methods for characterizing the quantity and orientation of fibers in UHPC elements are needed for assessing the impact of the placement methods and flow properties on the local resistance to tensile stresses. This presentation describes a method for analyzing fiber distribution and fiber orientation using two-dimensional (2D) images and compares the results to the information obtained from analyses of three-dimensional (3D) volumes. The fiber distribution is characterized in terms of fiber content and axial alignment factor, and examples of analysis are compared with mechanical response for different UHPC elements including flexural beam specimens, direct tensile test specimens, and a full-scale structural member. UHPC, fiber alignment, fiber orientation, fiber distribution, image analysis, flexural performance