ETL 1110-2-365
31 Aug 94
In cases where the application of service load has
the Handbook for Concrete and Cement published by
reduced the crack potential, there must be a reanalysis
the U.S. Army Engineer Waterways Experiment
without service loads to determine the crack potential
Station (WES) (1949a). Test methods identified as
for those monoliths constructed at early times when
RTH (Rock Testing Handbook) are Corps of Engi-
service load application is more than 1 year away.
neer methods found in the Rock Testing Handbook
(USAEWES 1990). The units listed in the following
discussion are those normally associated with the
g. Parametric studies. Material property combi-
respective material property/test method. The units
nations may be supplemented through the use of
input into to the ABAQUS program may vary; see
additional parametric studies. A parametric study is a
paragraph A-5a(4), Units, for further discussion.
rationally planned set of analyses used to gain a
better understanding of structural response through
the identification and understanding of the effects that
b. Concrete properties. The following thermal,
critical parameters have on the structure. The effects
mechanical, and physical properties must be deter-
of a parameter on the structure can be determined by
mined as input to a NISA. Some of the properties
varying that parameter in a set of analyses while
will be determined by laboratory testing and some
holding the other parameters constant. Likely candi-
will be assigned jointly by the materials and structural
dates for a parametric study are, but are not limited
engineers. Properties that are determined in
to, determination of the critical material property
laboratory tests should be representative of concrete
combination, analysis duration, type of analysis (i.e.,
mixtures containing project specific materials. The
plane stress or plane strain), critical lift sequence or
test data and curves defining the time relationships
configuration, analysis start time, critical material
should be documented in the concrete materials
properties, insulation requirements, and placement
design memorandum. The following properties will
temperatures. Results from single analyses within the
be determined in the laboratory prior to start of a
parametric study should be interpreted separately to
NISA.
gain an understanding of the structural response in
each analysis. Then comparisons of results from each
(1) Thermal properties.
analysis in the parametric study can be made and the
influence of each parameter identified. Once identi-
(a) Adiabatic temperature rise. An adiabatic
fied and documented, results and conclusions from
system is a system in which heat is neither allowed to
parametric studies can be used in subsequent NISA
enter or leave. The adiabatic temperature rise, there-
phases. For example, assume a goal of a current
fore, is the change in temperature due to hydration of
NISA study is to reduce construction costs through
the cementitious materials in a concrete mass when
relaxing controls on concrete placement temperatures.
adiabatic conditions exist. It is a measure of the heat
A parametric study is devised permitting only the lift
evolution of the concrete mixture and serves as the
placement temperature to vary. Results are analyzed,
loading in the heat-transfer analyses. In very large
and the highest acceptable placement temperature is
masses of concrete, temperatures near the center of
selected for subsequent use.
the mass will peak near the sum of the placement
temperature and the adiabatic temperature rise.
Nearer the surface of the placement, the peak temper-
A-3. Material Properties
ature will be lower and will be near ambient air tem-
perature. Adiabatic temperature rise is determined
a. General. Information on the thermal,
according to CRD-C 38 (USAEWES 1949a). The
mechanical, and physical properties are required for
rate of heat evolution depends on the amount and
the concrete mixtures, foundation materials, and air.
type of cementitious materials in the mixture and on
If the foundation includes piles, they will be modeled
the temperature of the test specimen at the beginning
in the analysis and their stiffness properties will be
of the test. Because of this dependence on the tem-
input into ABAQUS. Some of these properties are
perature of the test specimen, the total amount of heat
time dependent, while others are assumed to remain
generated at any given time will also be different.
constant with respect to time. Test methods identi-
The peak temperature and the shape of the curve can
fied as ASTM are American Society for Testing and
vary significantly for different concrete mixtures.
Materials, Philadelphia, PA, methods. Test methods
Therefore, concrete used in the test should closely
identified as CRD-C (Concrete Research Division-
represent concrete that will be used for the project
Concrete) are Corps of Engineers methods found in
and the placement temperature for the test should be
A-11
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