31 Dec 93
APPENDIX B: ANALYSES WITH NO CULVERT
(2) The final crack length computed using the
traditional method of analysis was 19.62 ft. The
In an effort to determine the effects of the large
fracture mechanics based prediction of 16.65 ft is
culvert located near the base of the monolith, a
only 15.1% less than the value of 19.62 ft computed
series of analyses was performed for a solid mono-
using the traditional analysis method. When the
lith in which the culvert was not considered. Anal-
culvert was considered, the discrepancy between the
ysis procedures were identical to those described in
final crack lengths was 43.7% (see Appendix A),
Appendix A. The open area of the culvert was
which is slightly more than three times the 15.1%
eliminated by simply adding elements and nodes to
of this case. The fact that the estimated crack
the mesh shown in Figure A-4 of Appendix A.
lengths are in much better agreement when the
Material properties and applied loads for this inves-
culvert is not considered indicates that the rigid
tigation were identical to those used for the analyses
behavior assumed by the traditional method of
in which the culvert was considered.
analysis more closely approximates the actual
behavior as the monolith becomes stiffer. This
should be expected since a solid monolith would
2. Analysis and Results
behave more like a rigid block than one with a
large culvert. Based on this observation, the
a. Estimation of crack length.
assumption of a rigid monolith in the traditional
method of analysis does not appear to be valid
(1) A series of nine analyses, each with a dif-
when a large culvert is present.
ferent specified crack length, was performed to
b. Normal stress profiles.
compute an initial estimate of the final crack length.
The prescribed crack lengths for these analyses
ranged from 6.0 ft to 18.0 ft in 1.5-ft increments.
(1) The normal stress profile along the base of
No analyses were performed for crack lengths
the monolith for a crack length of 16.65 ft is shown
greater than 18.0 ft because the value of KI for a =
in Figure B-2. In order to contrast the difference
18 ft was negative and KI was positive for all prior
between the traditional and proposed methods of
analyses. The final crack length of 16.65 ft was
analysis, the normal stress profile from the tradi-
found by re-meshing and comparing KI to KIc as
tional method of analysis is also included in
described in paragraph 3d(1) of Appendix A. The
Figure B-2. The distance along the base of the
results of each analysis are summarized in
monolith is measured from the toe of the monolith
Table B-1. The variations of KI and KII over the
to the heel of the monolith and a negative stress
range of crack lengths are shown in Figure B-1.
indicates compression. Comparison of the normal
Summary of Finite Element Analyses With No Culvert