Size Effects and the Dynamic Response of Plain Concrete

Abstract

This paper investigates the specimen size effect on the dynamic response of plain concrete. The report is based upon experimental data by the writers and others and considers results from creep tests on beams, beams under flexural impact, and cylinders under axial impact loading. Size effect is examined using Bažant’s size effect law and the multifractal scaling law, and both scaling models are able to capture the size effect on strength. For fracture energy, on the other hand, the size effect manifests itself only at impact rates. Under quasi-static loading, plain concrete in compression is less sensitive to the specimen size. But under impact, the compressive response appears to be more size dependent than flexure. However, upon accounting for the stress rate effects, the flexural response depicts a more significant size effect, similar to that seen at quasi-static rates.