Gradual Crushing of Steel Reinforced HPFRCC Beams: Experiments and Simulations

Abstract

While the tensile performance of high-performance fiber-reinforced cementitious composites (HPFRCC) has been extensively studied, the crushing behavior is less understood. Notably, crushing is an important load-reduction mechanism for reinforced HPFRCC flexural members that fail in a ductile mode, i.e., failure after gradual strain hardening of the steel reinforcement accompanied by gradual HPFRCC crushing. This study first investigates the crushing behavior of HPFRCC flexural members through experimental testing of two reinforced HPFRCC beams. The experimental program includes two types of HPFRCC materials: engineered cementitious composites (ECC) and ultra-high performance concrete (UHPC). The test results show that both ECC and UHPC gradually soften in compression after the initiation of crushing, which is in contrast to the more brittle crushing behavior typically observed in conventional concrete. In addition to the experimental investigation, a new HPFRCC compression model is implemented in a two-dimensional finite-element analysis to simulate the gradual compression softening behavior in reinforced HPFRCC flexural members. Different modeling strategies are compared and evaluated. Results show that the proposed model with an initial material flaw, the new compression model, and a hybrid-rotating/fixed-crack model best predict the reinforced HPFRCC structural performance, especially the failure mode and drift capacity.