New model advances understanding of stress–strain behavior in FRP-confined ultra-high-performance concrete

A recent research published in Engineering has unveiled a novel analysis-oriented stress–strain model that promises to revolutionize the way engineers understand and design with ultra-high-performance concrete (UHPC) confined by fiber-reinforced polymers (FRP). This significant advancement in concrete research, led by S.S. Zhang, J.J. Wang, Guan Lin, and X.F. Nie, provides a deeper insight into the compressive behavior of FRP-confined UHPC, addressing a critical gap in current structural engineering models.

UHPC has gained prominence in modern construction due to its exceptional strength and durability. However, understanding its behavior when confined with FRP materials has remained a complex challenge. Traditional models have successfully addressed the stress–strain relationships for normal-strength concrete (NSC) confined by FRP, but these models fall short when applied to UHPC.

The study, conducted by researchers from Huazhong University of Science and Technology and Southern University of Science and Technology, sought to bridge this gap by investigating the failure mechanisms of UHPC under concentric compression and developing a refined analysis-oriented model.

The researchers performed a series of experiments to examine how UHPC behaves under concentric compression when confined by FRP. Their findings revealed that the commonly used stress-path-independency assumption, which applies well to FRP-confined NSC, does not hold true for UHPC. This discrepancy led the team to rethink and modify the existing models to better represent the behavior of FRP-confined UHPC.

One of the major revelations was that the formation of major diagonal cracks in FRP-confined UHPC resulted in non-uniform lateral expansion. This phenomenon caused a decrease in the effective confining pressure from the FRP to the UHPC, challenging the applicability of stress-path-independency assumptions used for NSC.

To address these issues, the researchers developed a new model that incorporates the influence of stress-path dependency. By adjusting the confining pressure and including a new equation for the confining pressure gap, the team successfully accounted for this factor in their analysis-oriented model.

The proposed model was rigorously tested using a comprehensive database of collected test results. The validation process demonstrated that the new model accurately predicted the stress–strain behavior of FRP-confined UHPC. This accuracy marks a significant improvement over previous models and offers engineers a more reliable tool for designing and analyzing UHPC structures.

This study represents a major step forward in the field of structural engineering and concrete science. The introduction of an analysis-oriented model that considers stress-path dependency provides a more nuanced understanding of UHPC’s compressive behavior. This advancement not only enhances the design and safety of structures incorporating UHPC but also opens new avenues for future research.

The ability to accurately predict the behavior of FRP-confined UHPC will have profound implications for the construction industry, potentially leading to more efficient and safer designs for a variety of structural applications. Researchers and engineers can now leverage these insights to improve the performance and longevity of UHPC structures, driving innovation in concrete technology.

This research provides a valuable tool for engineers and researchers working with UHPC. As the construction industry continues to evolve, this new model promises to play a crucial role in shaping the future of high-performance concrete applications.

The paper “Analysis-oriented stress–strain models for ultra-high-performance concrete confined with fiber-reinforced polymer,” authored by S.S. Zhang, J.J. Wang, Guan Lin, X.F. Nie. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.08.002. For more information about the Engineering, follow us on X (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).