Numerical study on the low-velocity impact response of ultra-high-performance fiber reinforced concrete beams

Abstract

The material and structural behaviors of Ultra High-Performance Fiber-Reinforced Concrete (UHP-FRC) under a high strain rate loading are different than a quasi-static loading condition. Though, UHP-FRC has very high compressive strength compared to conventional concrete, the failure strain of UHP-FRC is not enough to withstand large plastic deformations under high stain rate loading such as impact and blast loading. Due to the high cost of large-scale experimental research of structural elements under impact loading, modeling of UHP-FRC girders using computer aided program has become a need. Hence, this study aims to develop a finite element model of UHP-FRC to simulate low-velocity impact phenomenon. The responses obtained from the numerical study are in good agreement with the experimental results under impact loads. Five different types of UHP-FRC beams were simulated under impact loading to observe the global and local material response. The key parameters investigated were the reinforcement ratio (ρ), impact load under various drop heights (h), and the failure phenomena. It was observed that higher reinforcement ratio showed better deflection recovery under the proposed impact. Also, for a specific reinforcement ratio, the maximum deflection increases approximately 15% when drop height decreases from 100 mm to 25 mm. Moreover, the applicability of concrete damage plasticity model for impact loading is investigated. The results also provide recommendations for predicting the location of the local damage in UHPFRC beams under impact loading.