@Article{sdhm.2026.083328,
AUTHOR = {Qinfeng Pan, Wei Zhang, Hao Chen, Lin Pang, Xiang Liu, Chun Chieh Yip},
TITLE = {Bond Behavior of NPR Bar/Steel Strands with Ultra-High-Performance Concrete},
JOURNAL = {Structural Durability \& Health Monitoring},
VOLUME = {20},
YEAR = {2026},
NUMBER = {4},
PAGES = {--},
URL = {http://www.techscience.com/sdhm/v20n4/67873},
ISSN = {1930-2991},
ABSTRACT = {Ultra-high-performance concrete (UHPC) exhibits high strength, toughness, and durability, making it an excellent candidate for integration with novel high-ductility, high-strength negative Poisson’s ratio (NPR) steel bars. This combination shows promising applications in the fields of bridges and buildings. This study investigates the bonding performance of various types of NPR bars (smooth NPR bars, spiral rib NPR bars, and NPR steel strands) with UHPC as the concrete matrix. It examines the effects of bond length, bar diameter, and NPR bar type on bonding performance, comparing these results with those of normal concrete (NC). A predictive model for the bonding performance of NPR bars with UHPC was developed. Results show that in the UHPC matrix, all types of NPR bars primarily exhibit pullout failure, with bond strength exceeding that of the NC matrix group by 47.07%. The use of NPR bars improves ductility, with all groups demonstrating better ultimate slip compared to traditional steel bars. An increase in bond length reduces the ultimate strength of all NPR bar types while simultaneously increasing ultimate slip. Similarly, a larger bar diameter decreases the ultimate strength of NPR steel strands by 32.32% and increases slip. During this process, the expansion effect of the strand wires complicates the loading conditions during pullout. Among the three NPR bar types, spiral rib NPR bars exhibit the highest ultimate strength but relatively low slip. In contrast, smooth NPR bars and NPR steel strands have lower ultimate strength but allow for greater slip. The parameter, empirical, and composite models developed in this study demonstrate strong predictive accuracy, with most models achieving an R<sup>2</sup> value above 0.7. These models reliably estimate the ultimate strength and slip of NPR bars in UHPC. These findings provide a solid theoretical foundation and practical guidance for the application of NPR bars in UHPC.},
DOI = {10.32604/sdhm.2026.083328}
}