EP 1110-2-12
30 Sep 95
section of the nonoverflow monolith with the greatest
be reanalyzed using a composite finite element-
height. The dam-foundation-reservoir system shall be
equivalent mass system model and general purpose
represented by a composite finite element-equivalent
finite element program in the final design.
mass system model for RCC dams subject to critical
seismic design conditions. For other conditions, the
b. Foundation and material investigations. The
dam-foundation-reservoir system may be character-
foundation conditions for the final design shall reflect
ized by either the standardized model using Chopra's
the latest exploratory coring and other foundation and
simplified method or the composite finite element
geology investigations. The final design shall be
model described above.
based on the RCC material properties obtained from
tests on core samples taken from test fill placements
b. Seismic and foundation investigations.
made with the proposed design mixes.
Appropriate investigations of the regional tectonics
and site seismicity shall be conducted at the prelimi-
8-6.
Evaluating Existing Dams
nary design stage. When required, the site-specific
design response spectra shall be developed in accor-
The dynamic analysis procedure for evaluating exist-
dance with paragraph 5-5c. Preliminary dam site and
ing dams is essentially the same as the combined
reservoir geology investigations shall be conducted
preliminary design and final design procedures for a
including exploratory corings and load testing to
new dam, except modification of the design discussed
determine foundation conditions and deformation
in paragraph 8-3b does not apply to existing dams.
modulii.
As with the design of new dams, the dynamic analy-
sis procedure shall utilize an analysis method with the
c. Tensile strength. For preliminary design, the
simplest attributes possible to determine if the exist-
tensile strength may be taken from Figures 3-1
ing dam is capable of responding to the design earth-
through 3-6 for the proposed basic RCC mix and for
quakes in an acceptable manner.
superior RCC mixes in the critical zones.
a. Material properties. Material properties of
d. Satisfying criteria. The preliminary design
the RCC for an existing dam, including tensile
procedure shall progress to the point where it
strength, shall be obtained from tests on core samples
becomes evident that the preliminary design will lead
taken directly from the dam.
to a final design that fully satisfies established perfor-
mance requirements and criteria.
b. Using available records. Exploratory coring
logs, laboratory test data, and field geologic test
8-5.
Final Design of New Dams
results conducted during design and construction
should be used for an existing dam and to provide
The final design of an RCC dam shall result in a
information needed to model the foundation. Reser-
design that satisfies the provisions of this EP. The
voir data should be used to determine the reservoir
dynamic analysis phase for RCC dams under critical
and tailwater elevations for earthquake load cases.
seismic design conditions shall be presented in an
appropriate feature design memorandum.
c. Special requirements and analysis methods.
The regional tectonics and site geology and seismicity
a. Final design analysis method. The dynamic
shall be investigated as required to develop a site-
analysis method for the final design shall evolve from
specific design response spectra in accordance with
the simple initial method described in paragraph 8-4a
paragraph 5-5c. The initial analysis of an existing
to more refined methods of design conditions as war-
dam shall utilize a composite finite element-
ranted. RCC dams analyzed by Chopra's simplified
equivalent mass system model. Existing dams shall
method during the preliminary design phase shall
not be analyzed by Chopra's simplified method.
8-6
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