Elucidation of Static Fracture Energy and Dynamic Tensile Performance of Hybrid Steel Fiber-Based Ultrahigh-Performance Concrete

Abstract

Ultrahigh-performance concrete (UHPC) has great potential for applications in civil and military structures due to its outstanding performance and ability to withstand impact and blast load. This performance can be attributed mainly to the materials and their proportions, especially metallic fibers. Hence, understanding the behavior of UHPC under static and dynamic conditions through the effect of hybridization of steel fibers is essential. Compressive strength and flexural strength were studied in quasi-static mode. In flexural mode, strain characterization was done using a digital image correlation (DIC) technique. Fracture studies were also conducted with notches using a crack mouth opening displacement (CMOD) technique. In high-strain mode, dynamic tensile strength was evaluated using a split Hopkinson pressure bar (SHPB) with a Brazilian disk. Owing to optimized hybridization, enhancement in (1) toughness, (2) energy absorption, (3) crack-resistance capacity, (4) reserve strength, (5) limit of proportionality, (6) fracture energy, (7) stress intensity factor, (8) tensile strain carrying capacity, and (9) dynamic tensile strength were observed. In the process, other findings in relation to fracture, strain rate, and dynamic increase factor were also exemplified. The SHPB dynamic tensile test results, as well as the technical information provided regarding UHPC’s hybrid steel fibers’ strength, failure, and fracture behavior, can be used to improve the design of UHPC building structures to protect against impact and blast attacks.