Behavior of FRP-confined ultra-high performance concrete under eccentric compression

• Published in: Composite structures 2021-01, Vol.256, p.113040, Article 113040
• Main Authors: Tian, Huiwen, Zhou, Zhen, Wei, Yang, Wang, Yongquan
• Format: Article
• Language: English
• Subjects: Confinement; Eccentric compression; Fiber-reinforced polymer (FRP); Fiber/matrix bond; Steel fiber; Ultra-high performance concrete (UHPC)
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2020.113040

This paper presents an investigation on the eccentric compressive behavior of fiber-reinforced polymer (FRP)-confined ultra-high performance concrete (UHPC). Twenty specimens with varied tube thicknesses and loading eccentricities were tested. The results indicated that nearly all specimens showed a strain-hardening behavior, except that several specimens with a very large loading eccentricity showed a strain-softening behavior. With the increase of the loading eccentricities, the load-carrying capacity and deformability exhibited a substantial reduction, while the tube thickness only showed a significant effect in concentric or small eccentricity cases. A finite element model was established, where UHPC was treated as a two-phase material and simulated with UHPC matrix and explicitly modeled steel fibers. An equivalent stress–strain relationship derived from the single fiber pullout test was proposed for the embedded steel fibers to provide a more accurate prediction for the fiber–matrix interfacial behavior. Based on a regression analysis of the experimental and numerical results, a design equation was developed to predict the ultimate load-carrying capacity of FRP-confined UHPC under eccentric compression.