Mesoscale Study on Dilation Behavior of Plain Concrete under Axial Compression

The dilation of concrete in the radial direction is crucial in understanding the failure process and the key to predicting the confining level of passively confined concrete. To better understand this problem, we established a mesoscale model of concrete by considering the random distribution of coarse aggregate and the different properties between mortar and concrete. The model’s validity was demonstrated by comparing with the stress–strain curves in code and the lateral–axial strain curves in test. The simulation results show that the lateral dilation is non-uniformly distributed along the specimen height and the circumferential direction of sections. Moreover, the deformation mainly occurs in the middle part of the specimen ranging from 3/8 to 5/8. The strength of concrete influences the stress ratio at maximum compressive strain, while it slightly influences the stress ratio at zero volumetric strain. The secant strain ratio is about 0.5 as the compressive stress reaches the strength of concrete. Compared with the simulation, the relationship between lateral strain and axial strain proposed by Teng and Binici shows excellent performance on the dilation trend prediction of plain concrete.