Biaxial behaviour of plain concrete subjected to dynamic compression with constant lateral stress

Abstract This study investigates the dynamic biaxial behaviour of concrete by testing more than 60 cubic specimens on a custom‐designed, servo‐hydraulic‐controlled machine. Each specimen was axially loaded in compression at a constant strain rate of 10–5, 10–4, 10–3 or 10–2 s–1 while two opposite side faces were subjected to a constant confining pressure and the other two side faces were free. The confining pressure applied to each specimen was 0, 30.5, 61.0 or 91.5 % of its uniaxial compressive strength. Test results indicate that the biaxial strength of concrete increases with strain rate at a reduced slope as confining pressure increases. The failure mode of the concrete specimens was basically unaffected by the strain rate. An empirical relation for the ultimate strength of concrete in a biaxial stress state was developed taking into account the effects of both confinement and strain rate.