Poisson’s ratio of concrete relates the transverse strain to the longitudinal strain in a concrete specimen under axial loads. When concrete is compressed, it undergoes volume reduction, causing longitudinal and vertical strains. The reduction in volume is due to the crushing of small aggregate sizes caused by applied loads. Poisson’s ratio of concrete remains constant and is used to determine the stress and deflection properties of structures like beams, plates, and shells.
What is Poisson’s Ratio of concrete?
The value of concrete’s Poisson’s ratio can vary depending on the type of specimen (dry, wet, or saturated) and loading conditions. When subjected to static loads, concrete generally has a lower Poisson’s ratio compared to when dynamic loads are applied. Under dynamic loads, the Poisson’s ratio of concrete typically ranges from 0.20 to 0.25, with higher values around 0.1 for high-strength concrete and lower values around 0.2 for low-strength concrete. In the design of concrete structures, a common value for Poisson’s ratio is taken as 0.2.
It is important to exercise caution and ensure that the Poisson’s ratio is compatible with the values used for the shear modulus of elasticity of concrete, as serious errors can occur if they are not compatible. Poisson’s ratio of concrete remains constant up to about 70% of its strength and can be determined through static modulus tests.
Additionally, dynamic methods such as ultrasonic pulse velocity and the fundamental resonant frequency of longitudinal vibration of a concrete beam can also be used to determine the Poisson’s ratio.