31 Aug 94
A2-3. Cracking Potential
c. If on or outside the surface, introduce a crack
perpendicular to the direction of the maximum princi-
Cracking potential is a quantitative measure of the
imminence of exceeding the cracking criteria. It is
equivalent to the ratio of l1 to the total length (l1 + l2),
d. In the direction perpendicular to the crack,
as shown in Figure A2-3, where l1 is the distance
the stress must then be set to zero, and the other
from the origin to the point (ε, σ) which reflects the
stresses must be modified to reflect that change.
actual principal stress and strain at a point in the
structure. The value (l1 + l2) is the length of the line
e. The stiffness matrix must then be modified to
from the origin to the failure surface which passes
reflect zero load carrying capabilities in that direction
through (ε, σ). The cracking potential is an indicator
until the crack closes and enters a compressive state.
of how near the current stress-strain state is to the
f. If the material enters a compressive state, the
crack is assumed to have closed and 100 percent of
the compressive stiffness is reinstated in the direction
perpendicular to the crack. Once the material is
placed in a tensile state again, the crack and a zero
The following is a brief step-by-step account of how
stress state is reintroduced at this location.
the cracking model operates within the code.
a. Plot the point represented by the principal
stresses σ1 and σ2 and their respective principal
strains ε1 and ε2. Check if these points are inside or
a. Garner, S. B., Bombich, A. A., Norman,
C. D., Merrill, C., Fehl, B., and Jones, H. W. 1992.
outside the surface.
"Nonlinear, Incremental Structural Analysis of
Olmsted Locks and Dams - Volume I, Main Text,"
b. If inside the surface, no cracking occurs.
Technical Report SL-92-28, U.S. Army Engineer
The cracking potential is calculated, and the next
Waterways Experiment Station, Vicksburg, MS.
b. Truman, K. Z., Petruska, D., and
Ferhi, A. 1992. "Evaluation of Thermal and Incre-
mental Construction Effects for Monoliths AL-3 and
AL-5 of the Melvin Price Locks and Dams," Contract
Report ITL-92-3, U.S. Army Engineer Waterways
Experiment Station, Vicksburg, MS.
Figure A2-3. Cracking potential generation for a
specific cracking failure surface