10.1 : コンクリートの弾性

When a concrete specimen is subjected to moderate or high magnitude uniaxial compressive or tensile stresses,  the resulting strain varies non-linearly with the applied stress.

Upon unloading the specimen, the resulting stress-strain curve traces a different path than during loading, forming a hysteresis loop. This demonstrates the material's non-linear and non-elastic behavior.

Generally, the slope of the linear portion of the stress-strain curve represents the value of the modulus of elasticity.

Since the concrete stress-strain curve is non-linear, its static modulus of elasticity is computed using different methods.

A line tangent to any point on the stress-strain curve is drawn, and its slope gives the tangent modulus specifically for loads near the considered stress value.

From the origin, a line is drawn to a point on the curve corresponding to 40 percent of the concrete's failure load, and its slope gives the secant modulus.

The point on the curve representing a strain of 50 microinches per inch is joined with the point on the curve representing 40 percent of the concrete's ultimate load, using a line, and its slope gives the chord modulus.