Page 421 - Mechanics of Asphalt Microstructure and Micromechanics
P. 421
Characterization and Modeling Anisotropic Proper ties of Asphalt Concrete 413
FIGURE 12.15 Analytical model of the beam testing.
Where κ is the curvature. For a beam with a single elastic modulus, i.e., the compres-
sive modulus equals the tensile modulus, the location where strain equals to zero, or the
so-called neutral axis, is at the middle of the height for a cross-section shown in Figure
12.15a. When the compressive modulus is different from the tensile modulus, Equation
12-10 still holds, but the neutral axis no longer coincides with the mid-height. In Figure
12.15b, the neutral axis is off the middle of the height and distance a away from the bot-
tom fiber and b from the top fiber. The strain corresponding to distance a is the largest
tensile strain and is denoted as e t . Similarly, e c is used to denote the largest compressive
strain at distance b. With the geometry in Figure 12.15b, it is obtained that:
ε a
t == r (12-11)
ε b
c
