PROPERTIES OF CONCRETE SUBJECTED TO IMPACT

For rational design of concrete structures subjected to impact and impulsive loading, the constitutive properties of concrete over a wide range of strain rates are required. With this aim in mind, concrete and fiber reinforced concrete beams were tested in a drop-weight, instrumented impact testing machine. During the impact event, loads, deflections and strains were monitored. The modulus of rupture at high strain rates obtained in impact loading was up-to twice that observed at low strain rate (static loading). With increasing strain rate, the load-deflection curves became less nonlinear. The energy absorbed by fiber reinforced concrete beams was as much as 100 times that for unreinforced beams. The influence of matrix mix proportions, relative humidity during curing and the type of fibers (steel, polypropylene and glass) on impact properties are presented. Cracking appears to be the major process responsible for the observed strain-rate effects in concrete and fiber reinforced concrete. Copyright © 1983 ASCE.