Tensile behavior of hybrid fiber-reinforced high-strength concrete based on a 3D mesoscopic model

To investigate the impact of hybridizing polypropylene (PP) microfibers with wavy steel fibers (WSF) and coarse polypropylene fiber (CPP) on the crack resistance of high-strength concrete (HSC), this study employed a combination of mesoscale finite element analysis and uniaxial tensile tests. Based on the gravity accumulation method, a four-phase mesoscale model incorporating different aggregate morphologies and fibers was established. The fracture process was simulated using a cohesive zone model and fiber pull-out curves. The research findings indicate that in fiber-free HSC, aggregate morphology does not affect the tensile strength and elastic modulus, but the interlocking of sharp-angled aggregates exacerbates macroscopic brittle fracture. In fiber-reinforced HSC, aggregate morphology has no significant impact on macroscopic mechanical properties; aggregates with fewer vertices facilitate uniform fiber distribution and enhance bridging effects. The hybrid use of PP-CPP increases the ultimate strength of HSC by 11.9%-15.8%, while PP-WSF can enhance it by 14.4%-25.8%, with the latter showing a superior enhancement effect. For structures subjected to extreme loads, the PP-WSF 1.0% system is recommended to control cracking and delay damage; in corrosive environments or when extreme loads are infrequent, the more economical PP-CPP 1.0% system is suggested. © 2026 Elsevier Ltd.