Using Hopkinson pressure bar to perform dynamic tensile tests on SFRC at medium strain rates

摘要

The dynamic tensile strength of steel fibre reinforced concrete is experimentally investigated. Cylindrical specimens are first fabricated with three different fibre volume fractions of 0, 0·75% and 1·5%. These specimens are then tested by using the Hopkinson pressure bar technique. Their dynamic tensile strengths are measured under medium strain rate impact. In these tests, the stress histories are recorded by way of the strain gauges symmetrically mounted on the specimen and the post-test fracture modes are photographed. The test results indicate that the superposition of waves induces first compressive stress and then tensile stress. Once the tensile stress reaches its critical value, a spalling phenomenon occurs. Both volume fraction of fibres and strain rate exert a significant influence on the dynamic tensile strength of concrete. Furthermore, the strain-rate-induced enhancement of tensile strength is related to the compressive strength of the concrete matrix.