התנהגות של רכיבי UHPC מבניים - אנליזה וגישות לתכן

This report presents an experimental study investigating the behavior of large-scale reinforced concrete beams made of Ultra-High-Performance Concrete (UHPC). The study involved 12 full-scale flexural tests, accompanied by material property tests. A variety of UHPC mixes were examined, some incorporating steel fibers with different geometries and dosages, and others using different aggregate types. The main parameters studied were fiber type, fiber volume fraction, aggregate type (coarse vs. fine), and the longitudinal reinforcement ratio.
Advanced measurement techniques were employed, combining traditional mechanical gauges with digital image correlation (DIC) systems, enabling detailed monitoring of displacements and crack development throughout the loading process. The experimental results were analyzed with respect to flexural capacity, cracking patterns, deformations, and failure modes—including concrete crushing, reinforcement rupture, and localized crack propagation.
Key findings highlight the significant impact of fiber type on the ductility and failure mode of UHPC beams: short fibers improved the compressive strength by bridging micro-cracks, while long fibers enhanced post-cracking performance, leading to more ductile behavior but also more pronounced localization effects.
The study provides valuable data for understanding the structural performance of UHPC beams and underscores the need to adapt the current Israeli design standards to better account for the unique properties of UHPC. The findings lay a foundation for further research into optimizing UHPC structural elements and developing reliable engineering tools for practical design.