multiPlas - Dynardo GmbH

3.3.7.2 Nonlinear stress-strain relation under tensile load perpendicular to the bed joints
For the behaviour under tensile stress perpendicular to the bed joints a stress-strain relation with
exponential softening is available. The stress-strain relation is shown in Fig. 3-19. The conclusions, that
are done in 3.3.6.2 are valid here as well.
Fig. 3-19 stress-strain relation under tensile load perpendicular to the bed joints
3.3.7.3 Nonlinear stress-strain relation in case of shear load of bed joint
The shear failure of the bed joints, which could be observed in the test case, can be described by an
exponential degradation of the cohesion C and linear reduction of the friction angle φ0 to a residual
friction angle φr. The corresponding, assumed stress-strain line is shown in Fig. 3-20. The softening
model for the cohesion C was chosen analogical to the approach described in chapter 3.3.6.2. Hereby it
is assumed that for completely diminishing of the cohesion, a fracture energy GIIfJ (mode II – adhesionshear-strength)
has to be dissipated. This has been experimentally established by van der Pluijm [6-27].
The tension and shear softening are synchronized.
Fig. 3-20 Nonlinear stress-strain relation in case of shear of bed joint
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USER’S MANUAL, January, 2013