Experimental and Numerical Study of Ultra-High-Performance Fiber-Reinforced Concrete Column Subjected to Axial and Eccentric Loads
Ultra-high-performance fiber reinforced concrete (UHPFRC) is a specially formulated cement-based composite characterized with an ultra-high compressive strength (fc’ = 240 MPa) and a low water-cement ratio (W/B= 0.2). With such material characteristics, UHPFRC is favored for the design and constructions of structures required high structural performance and slender geometries. Unlike conventional concrete, the structural performance of members manufactured with UHPFRC has not yet been fully studied, particularly, for UHPFRC columns with high slenderness. In this study, the behaviors of slender UHPFRC columns under concentric or eccentric load will be investigated both experimentally and numerically. Four slender UHPFRC columns were tested under eccentric loads with eccentricities, of 0 mm, 35 mm, 50 mm, and 85 mm, respectively, and one UHPFRC beam was tested under four-point bending. Finite element (FE) analysis was conducted with concrete damage plasticity (CDP) modulus to simulating the load-middle height or middle span deflection relationships and damage patterns of all UHPFRC members. Simulated results were compared against the experimental results and observation to gain the confidence of FE model, and this model was further extended to conduct parametric studies, which aim to investigate the effects of slenderness regarding failure modes and load-moment interaction relationships. Experimental results showed that the load bearing capacities of the slender columns reduced with an increase in eccentricity. Comparisons between load-middle height and middle span deflection relationships as well as damage patterns of all UHPFRC members obtained both experimentally and numerically demonstrated high accuracy of the FE simulations. Based on the available FE model, the following parametric study indicated that a further increase in the slenderness of column resulted in significant decreases in the load-bearing capacities, ductility index, and flexural bending capacities.
 T. Xie, C. Fang, M. S. Mohamad Ali, and P. Visintin, “Characterizations of autogenous and drying shrinkage of ultra-high performance concrete (UHPC): An experimental study,” Cement and Concrete Composites, vol. 91, pp. 156–173, 2018.
 D. Y. Yoo, N. Banthia, Y. S. Yoon, “Effectiveness of shrinkage-reducing admixture in reducing autogenous shrinkage stress of ultra-high-performance fiber-reinforced concrete,” Cement and Concrete Composites, vol. 64, pp. 27–36, 2015.
 F. Baby, P. Marchand, M. Atrach, F. Toutlemonde, “Analysis of flexure-shear behavior of UHPFRC beams based on stress field approach,” Engineering Structures, vol. 56, pp. 194–206, 2013.
 G. H. Mahmud, Z. Yang, A. M.T. Hassan, “Experimental and numerical studies of size effects of Ultra High Performance Steel Fibre Reinforced Concrete (UHPFRC) beams,” Construction and Building Materials, vol. 48, pp. 1027–1034, 2013
 F. Baby, P. Marchand, F. Toutlemonde, “Shear Behavior of Ultrahigh Performance Fiber-Reinforced Concrete Beams. I: Experimental Investigation,” Journal of Structural Engineering, vol. 140, no. 5, 2014.
 F. Lachance, J. P. Charron, and B. Massicotte, “Development of Precast Bridge Slabs in High-Performance Fiber-Reinforced Concrete and Ultra-High-Performance Fiber-Reinforced Concrete,” ACI Structural Journal, pp. 929–939, 2016.
 S. G. Millard, T. C. K. Molyneaux, S.J. Barnett, and X. Gao, “Dynamic enhancement of blast-resistant ultra high performance fibre-reinforced concrete under flexural and shear loading,” International Journal of Impact Engineering, vol. 37, pp. 405-413, 2010.
 M. Empelmann, M. Teautsch, and G. Steven, “Expanding the application range of RC-columns by the use of UHPC”, Tailor Made Concrete Structures, pp. 461-468, 2008.
 H. O. Shin, Y. S. Yoon, S. H. Lee, W. D. Cook, and D. Mitchell, “Effect of steel Fibers on the Performance of Ultrahigh-Strength Concrete Columns”, Journal if Materials in Civil Engineering, vol. 27, no. 4, 2015.
 H. O. Shin, K. H. Min, D. Mitchell, “Confinement of ultra-high-performance fiber reinforced concrete columns”, Composite Structures, vol. 176, pp. 124-142, 2017.
 H. O. Shin, K.H. Min, D. Mitchell, “Uniaxial behavior of circular ultra-high-performance fiber-reinforced concrete columns confined by spiral reinforcement”, Construction and Building Materials, vol. 168, pp. 379-393, 2018.
 M. M. Hosinieh, H. Aoude, W. D. Cook, and D. Mitchell, “Behavior of ultra-high-performance fiber reinforced concrete columns under pure axial loading”, Engineering Structures, vol. 99, pp. 388-401, 2015.
 G. Steven, and M. Empelmann, “UHPFRC-Columns with high-strength longitudinal reinforcement (in German)”, Concr Reinf Concr, vol. 109, no. 5, pp. 344-54, 2014.
 C. C. Hung, F. Y. Hu, and C. H. Yen, “Behavior of slender UHPC columns under eccentric loading”, Engineering Structures, vol. 174, pp. 701-711, 2018.
 K. Wille, A. E. Naaman, and S. EI-Tawil, “Properties of strain hardeningultra high performance fiber reinforced concrete (UHP-FRC) under direct tensile loading,” Cement and Concrete Composites, vol. 48, pp. 53–66, 2014.
 S. J. Foster, M. M. Attard, “Strength and Ductility of Fiber-Reinforced High-Strength concrete columns,” Journal of Structural Engineering, vol. 127, no. 1, pp. 28-34, 2001.