Mesoscale simulation of compression-induced cracking and failure of ASR-damaged concrete with stirrup confinement

Abstract

The alkali-silica reaction (ASR) is a durability concern that can lead to expansion and cracking of concrete structures. ASR damage affects the physical characteristics of the concrete itself, although the load-carrying capacity of an RC structure may be maintained because the reinforcement continues to confine the core concrete. However, if the combined effect of expansion damage and external loading were to result in reinforcement rupture, this would prejudice the safety of a structure. To study this phenomenon, the discrete numerical simulation method 3D RBSM is used to carry out a parametric study of the compressive failure of concrete with three ASR damage levels under confinement. Stirrups with normal yield strength and with elastic behavior are investigated. The ASR expansion and cracking behavior for concrete with different confinement scenarios are presented and discussed. Following that, the compressive failure of concrete with ASR damage and the effect of stirrup confinement are studied. The simulated stress–strain relationships for cases without ASR damage are well fitted by a theoretical prediction model. As for elastic modulus and compressive strength, it tends to decrease with increasing ASR expansion whatever the confinement conditions. For models confined by stirrups, the degradation of compressive strength is delayed. Visualizations of internal stress, concrete crack propagation and stirrup strain development are obtained from the simulations and these are discussed. It is found that the confinement effect of elastic stirrups is greater than that of stirrups with normal yield strength. Further, the strain distribution on inner and outer surfaces of stirrups which is hard to be monitored in experiments is extracted. Stress concentrations arise at the inner radius of the stirrup bends, which is consistent with observations of real structures and could lead to rupture at these locations.