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© 2019 Chinese Academy of Sciences. All rights reserved. Ultra-high performance steel fiber-reinforced concrete is an innovative cement-based composite material with excellent mechanical properties and outstanding potential in resisting extreme loads. In this study, a meso model of ultra-high performance steel fiber-reinforced concrete specimen, which consists of cement mortar and fibers, is developed to numerically simulate Split Hopkinson pressure bar (SHPB) tests for investigation of behavior of ultra-high performance steel fiber-reinforced concrete material under impact loading. The software LS_DYNA is used to perform the numerical simulation of dynamic tests. A good agreement is observed between the simulated results and experimental results. After the meso model is validated with static compression and split tension tests, SHPB tests are numerically modelled and the stress-strain history is interpreted in the meso-scale level. The influence of fiber on ultra-high performance steel fiber-reinforced concrete in dynamic tests is investigated. Within a reasonable range of steel fiber volume ratio (optimum volume ratio ranges from 0%-2.5% for micro steel fiber), the dynamic strength of ultra-high performance steel fiber-reinforced concrete increases significantly with the increase of steel fiber volume ratio, however, the contributions of fibers to Dynamic Increase Factors (DIF) of ultra-high performance steel fiber-reinforced concrete are constantly lower than those of conventional concrete material. The proposed model qualitatively and quantitatively predicts the material static and dynamic behaviors, and also gives insights on the fiber reinforcement effect in the concrete matrix. In this study, the dynamic constitutive relationships of ultra-high performance fiber-reinforced concrete are derived for predicting the dynamic strength of ultra-high performance fiber-reinforced concrete with different steel fiber volume ratios and strain rates. |
