ETL 1110-2-536
31 Dec 94
concrete, and the state of stress of the material.
notable was the analysis of Lock and Dam 26 near
Further, certain material properties exhibit nonlinear
St. Louis, Missouri, and the current design of
performance and somewhat unusual behavior at early
Olmsted Locks and Dam on the Ohio River. Several
ages. Consequently, definitive analyses of mass
concerns have been raised regarding the implementa-
concrete structures require a very complex analysis
tion of the ETL. The analytical process, as outlined
procedure requiring the definition of many variables.
in the ETL, is extremely comprehensive and expen-
sive. Certainly, not all Massive Concrete Structures
(2) A further complicating factor is that most
require a NISA to be performed. The results of this
mass concrete structures, such as dams, are con-
study can be used to determine the applicability of
structed over a long period of time. Consequently,
the current ETL guidance for future projects that may
thermal stresses develop during the construction phase
or may not require a NISA be performed.
and may be significantly affected by subsequent
construction activities.
A-3. Zintel Canyon Dam Thermal Cracking
(3) The evolution of an analysis package to
Evaluation
adequately model these variables has been a long and
tedious process. One of the earliest attempts to
a. General. The purpose of performing a ther-
develop an analysis system was in 1966 during the
mal cracking evaluation for Zintel Canyon Dam was
design of Dworshak Dam. A finite element analysis
to determine the consequent cracking of the structure
package was developed, under contract, by research-
resulting from thermally generated volume changes.
ers at the University of California, Berkeley. This
Since the evaluation was performed some time after
system was likely one of the first such analysis tools
the construction of the dam, actual conditions, such as
ever developed. Over the years, the finite element
ambient temperatures, RCC placing temperatures, and
analytical process has progressed to the point where
placing schedules were used in the model. However,
many commercial vendors have provided quite
additional laboratory work to characterize RCC mate-
sophisticated analytical tools for the evaluation of
rials was not done because of limited funds. This
stress and strain in concrete structures. Unfortu-
included creep properties, thermal properties, and
nately, most of these systems are general purpose
tensile strain capacity. Instead, these material proper-
computer codes that do not address the specific issues
ties were estimated. In addition, the limited access to
of the time-dependent behavior of mass concrete.
computer resources necessary to perform the analyses
further limited the depth of the investigation.
(4) More recently, the Corps of Engineers has
initiated the development of supplemental codes and
b.
Project description.
techniques to enhance and refine the analytical pro-
cess. The Corps selected for general use, ABAQUS,
(1) Zintel Canyon Dam is a straight axis con-
a general purpose finite element code. ANATECH
crete gravity structure. The length of the structure is
Research Corporation, under contract to the Water-
520 ft across at the crest and 126 ft above the foun-
ways Experiment Station (WES) developed software
dation at the deepest point. The structure is con-
subroutines to be used with the ABAQUS general
structed of 70,600 cu yd of RCC. The outflow
purpose finite element code. These subroutines were
spillway is 160 wide with a crest 16 ft below the top
designed to allow the user to input accurate, time
of the dam. The spillway flows are contained by
dependent and cracking material properties of con-
cast-in-place concrete training walls anchored to the
crete into the ABAQUS model.
RCC mass and RCC gravity training walls bordering
the stilling basin. The dam, stilling basin, and stilling
(5) ETL 1110-2-324 dated 30 March 1990, "Spe-
basin training walls are founded on basalt rock (see
cial Design Provisions for Massive Concrete Struc-
appendix C for a more complete project description).
tures," was published, providing policy guidance to
designers for execution of a NISA for the design of
(2) The project provides flood protection to the
mass concrete structures.
city of Kennewick, Washington. It is located on
Zintel Canyon, a 19-square mile water course which
b. Applicability of ETL-1110-2-324. The guid-
threatens the city with winter snow melt and summer
ance provided by this ETL has been followed in the
thunderstorm events. The water course is otherwise a
analysis and design of several structures. Most
A-2
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