Prediction of tensile response for ultra-high-performance concrete with a strengthen fiber/matrix interface based on the Weibull stochastic process

Herein, the tensile response of ultra-high-performance concrete (UHPC) is investigated based on two types of nano-SiO2 coated steel fibers with the average bonding strength of 9.96 MPa (NSI) and 16.27 MPa (NSII), respectively. The experimental results reveal that the interface enhancement is beneficial to the macro-mechanical properties of UHPC. Especially for the tensile behavior, the group with 2 vol% of NSII fibers has a 54.03%, 48.65%, and 69.63% in initial fracture strength, peak strength, and toughness. A micromechanical model that considered fiber fracture, critical embedded length, and fiber packing thickness was developed to simulate single crack tensile behavior of UHPC. The bridging stress and fracture energy for various of fiber content and interfacial bonding strength is discussed. Further, the tensile response of UHPC is simulated that considered the randomness of the strength distribution by the Weibull stochastic process. The tensile strength and toughness are well predicted.