A new dynamic testing method for elastic, shear modulus and Poisson’s ratio of concrete

• The position to paste strain rosette for dynamic test of concrete was determined.
• Steady-state excitation method was used and was proved reliable by static experiment.
• “Mode shape coefficient” for concrete was proposed.
• Formula of first-order torsional frequency of free slab was derived.
• Dynamically measured concrete properties follow the relationship given by E = 2G(1 + μ).

In this work, an energy-based method was used to derive the correlation between concrete shear modulus and torsional frequency of free slab based on first-order torsional mode shape of free slab. The relationship between dynamic elastic modulus of concrete and first-order bending frequency of free slab was also obtained. According to stress and strain analysis of first-order bending mode of concrete cantilever slab and the physical relationship between stress and strain under state of plane stress, the dynamic method for testing Poisson’s ratio μμ of concrete was proposed. For the concrete with a compressive strength of 22.6 MPa, a transient excitation method was used to determine its dynamic elastic modulus E and shear modulus G; and a steady-state sine excitation method was used to determine its dynamic Poisson’s ratio μ. The results of dynamic test showed that the ratio of shear modulus G and elastic modulus E is 0.403; elastic modulus E, shear modulus G and Poisson’s ratio μ  , follow the relationship given by E=2G(1+μ)E=2G(1+μ).