Title: Shear Strength Equation and Database for High-Strength HPFRC and UHPC Beams Without Stirrups

Author(s): Manuel Bermudez and Chung-Chan Hung

Publication: Structural Journal

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Keywords: beam shape; closed-form equation; fiber distribution; high-performance fiber-reinforced concrete (HPFRC); hybrid fibers; machine learning (ML); shear transfer mechanism; size effect; ultra-high-performance concrete (UHPC)

DOI: 10.14359/51740716

Date: 3/22/2024

Abstract:
The study presented a shear strength equation for high-strength high-performance fiber-reinforced concrete (HS-HPFRC), including ultra-high-performance concrete (UHPC). This equation was designed for straightforward implementation, catering to the regular tasks of engineers. It considers various influences on shear transfer mechanisms, including fiber bridging, fiber distribution, dowel action, cross-sectional shapes, and beam size effects. The equation does not rely on uniaxial tensile tests or inverse analysis of flexural tests; instead, it considers the statistical impact of fibers on shear strength. To generate the coefficients for this semi-empirical closed-form equation, an evaluation database of 118 HS-HPFRC and UHPC beams was constructed. The evaluation results revealed that the proposed equation has a mean of 1.00 and a correlation coefficient of 0.92, indicating low variation and high predictive accuracy. Furthermore, it outperformed existing equations and matched the accuracy of the machine learning-based models including SVM, RF, and ANN, despite its comparatively simpler expression.