Inhomogeneous mechanical behaviour of concrete subjected to monotonic and cyclic loading

Abstract

The mechanical behaviour of different parts (top, middle and bottom) of concrete exposed to monotonic and cyclic loading is investigated through laboratory testing. Strain evolution and energy dissipation are found inhomogeneous at different parts of the sample during compressive cyclic loading. The middle part of sample shows larger residual strain rate and dissipated energy than the top and bottom parts when larger load levels are applied. The disparity between the middle part and top/bottom parts reaches the peak value at peak strength. Based on two different cyclic loading strategies, it is concluded that the maximum load level has more pronounced effect on energy dissipation than the minimum load level. The evolution of P-wave speed during cyclic loading is also found inhomogeneous, a new definition of P-wave ratio is proposed as an effective fatigue failure precursor. The failure patterns of concretes subjected to monotonic and cyclic loading are presented, and it is shown that size and type of cracks is directly related to the loading methods.