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7.4 Determination of Chain Parameters
During the evaluation of elements and their properties,
DIANA uses indirect input of creep curves or relaxation curves
to generate direct input of Maxwell or Kelvin Chains by a curve fit.
The general form of indirect input is the discrete function
for creep or relaxation [§7.4.1].
Special creep functions are available from the main Model Codes for
concrete [§7.4.2].
Experienced users can overrule the
default settings used for the translation from indirect to
direct input, by specification of the following input.
Translation parameters (syntax)
![\begin{figure}\centering
\begin{tabbing}
\texttt{'MATERI'}
\\ [-1.0ex]
\rule{14...
...nf10}}\(_{n}\,\) \texttt{\textit{nstep}}\(_{n}\,\){]} \end{tabbing} \end{figure}](img1332.png)
- MAXWEL
-
indicates that generation of direct input for a Maxwell Chain is requested.
- KELVIN
-
indicates that generation of direct input for a Kelvin Chain is requested.
If neither MAXWEL nor KELVIN is specified,
DIANA will choose MAXWEL for non-aging curves and
KELVIN for aging creep curves.
A Kelvin Chain performs best in creep dominated problems,
a Maxwell chain in relaxation dominated problems.
For both models nchain is the maximum number of
units
nc
in the generated chain.
(
nc 
10
) [
nc = 10
] If the value for
nc
is too large for a unique fit,
DIANA will decrement it automatically.
- INITIM
-
t0eva is the start time of the creep or relaxation curve.
This value is only used in combination with specific concrete
creep models to indicate the start of the curve fit.
For concrete creep models the default is
t0 = 10-5
days.
- RLXPAR
-
are parameters additional to INITIM to define
logarithmic distributed sampling ages
for input of specific concrete creep models.
They define the sampling ages for the curve fit [Fig.7.1]:
Figure 7.1:
Sampling ages, curve fitting concrete creep
 |
nf10 is the number [
n10 = 10
]
of time steps n10
per factor 10 in age
(
n = 10nc + 1
)and nstep is the total number of time steps n
.
For generation of Maxwell Chains they also define the sample ages
for the internal transformation of a creep
diagram to a relaxation diagram.
RLXPAR is not used for generation of Kelvin Chains
from discrete creep diagrams or Maxwell Chains from discrete diagrams.
In those cases the sampling ages for the curve fit are directly
defined by the discrete diagram.
(file.dat)
'MATERI'
1 INITIM 1.E-2
RLXPAR 2 10
This example leads to the following sampling ages:
0, 0.01, 0.03162, 0.1, 0.3162, 1.0, 3.162, 10, 31.62, 100.
Subsections
Next: 7.4.1 Discrete Function
Up: 7. Viscoelasticity
Previous: 7.3 Kelvin Chain
Contents
Index
DIANA-9.3 User's Manual - Material Library
First ed.
Copyright (c) 2008 by TNO DIANA BV.