Tensile behavior of ultra-high performance concrete: Analytical model and experimental validation

Abstract

An analytical model is proposed to predict the tensile behavior of ultra-high performance concrete (UHPC) considering the pullout behavior of single fiber in matrix. The fiber pullout behavior is modeled from the work mechanisms of stress transfer at the matrix-fiber interface. The effect of fiber orientation, fiber snubbing, and matrix spalling on the tensile responses of UHPC is investigated by a parametric study, and a fiber reinforcement efficiency function α is derived to describe the combined effect. The fiber characteristics, interfacial bond strength, and fiber reinforcement efficiency show significant influence on the tensile strength and ascending branch of tensile stress-crack width curves, while some other model coefficients affect the shape of curves. The accuracy of the proposed analytical model is validated with the experimental direct tension test of UHPC, and good agreements are achieved between the analytical and experimental tensile responses. An underestimated tensile strength is observed when the prediction model is utilized with a lower volume fraction of fiber due to less group effect. The analytical model proposed can be used to effectively predict the tensile behavior of UHPC once their basic constituent material properties and single fiber pullout data are known and to better design the UHPC in tension.