10.2 : معامل المرونة الديناميكي

Stress analysis in concrete structures prone to dynamic and impact loading employs the dynamic modulus, which is greater than the static modulus of elasticity of the concrete.

The dynamic modulus of elasticity is determined using a sonic test where a concrete beam of standard dimensions is prepared and clamped at its center.   

One end of the beam is connected to an electromagnetic exciter unit designed to initiate vibrations, while the other end is connected to a pick-up for detecting these vibrations, which are then amplified and measured using an indicator.

The beam resonates at the fundamental frequency and is verified by the maximum deflection recorded in the indicator.

The value of the fundamental frequency, along with the values of the beam's length and density, is used to compute the concrete specimen's dynamic modulus of elasticity.

Alternatively, from the stress-strain curve of concrete, the initial tangent modulus is determined by drawing a tangent at the curve's origin and calculating its slope, which gives an approximate value of the dynamic modulus of elasticity of the concrete specimen.