STRENGTH ENHANCEMENT IN PARTICULATE SOLIDS UNDER HIGH LOADING RATES

The so-called 'strain-rate effect' in any material has been investigat ed here from a structural dynamics point of view. Starting with lumped -mass models (SDOF and 2-DOF) and assuming a rate-independent failure criterion, it is shown here how a high loading rate produces an effect of strength enhancement in any massive elastic material and how failu re takes place in a stronger component of a system as the loading rate increases. Extrapolating the concept of an equivalent elastic modulus as introduced in lumped-mass models and extending the analysis to a s emi-infinite elastic continuum, an algorithm has been schematized to e valuate an overall equivalent elastic modulus of a concrete body under the influence of high loading rate treating the concrete as a two-com ponent solid mixture consisting of cement paste matrix and aggregates.