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Up: 7.4 Determination of Chain
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Index
Subsections
DIANA offers concrete creep models for American,
European and Dutch codes as described in the next sections.
A customized creep function may be specified via a user-supplied
subroutine [§7.4.2.4].
See Chapter 20 for background theory.
Before describing the input syntax for the various model codes,
we first give some important notes on units and aging.
- Units
- of the input data for the concrete creep models
(day, MPa, mm,
°C
)
refer to the codes and are independent of the units in other input data
or commands.
If a time unit other than SI (seconds) is used for other input data
or commands, then you must specify the time unit that you used in table
'UNITS' [Vol. Analysis Procedures].
- Aging
-
of young concrete causes a rapid reduction of elastic
and creep deformation by loading at later ages.
The model codes therefore give different superposable creep curves for
loading at different young concrete ages.
The optionally generated age-dependent chains can model
these different creep curves.
Usage of the option is recommended for loading at young concrete ages.
Kelvin is the default for aging, Maxwell for non-aging.
Note:
there is a difference between element age and concrete age.
The concrete age is measured from the moment of casting,
and is used inside input for Model Codes.
The element age is measured from the birth
of the element, and is used inside (generated) input of discrete functions.
Concrete age will always be larger than the element age, to ensure an initial
stiffness at element birth.
Model Codes (syntax)
- CREEPN
-
code indicates the model code for the creep function:
MC1990 for the European CEB-FIP Model Code 1990 [§7.4.2.1],
ACI209 for the American Concrete Institute code 209
[§7.4.2.2],
NN6720 for the Dutch NEN 6720 code [§7.4.2.3].
7.4.2.1 CEB-FIP Model Code 1990
The MC1990 code
descriptor indicates the creep function
according to the European CEB-FIP Model Code 1990 [16].
(syntax)
- YOUN28
-
e28 is the Young's Modulus of concrete (in MPa)
at the age of twenty-eight days.
DIANA determines the Young's Modulus at ages of loading from this value.
- FCM28
-
fcm28 is the mean compressive strength
fcm
(in MPa) of concrete at the age of twenty-eight days.
- H
-
notsiz is the notational size of the member h
in mm,
h = 2Ac/u
, with
Ac
the cross-section
and u
the perimeter in contact with the atmosphere.
- LODAGE
-
[
tlo = 28
]
tlo is the concrete age
tlo
at loading in days.
Determines the creep curve used for the generation of non-aging chains.
- AGING
-
indicates that aging chains must be generated:
tel is the concrete age
tel
in days
at the birth of the element.
[
tel = 1
]
- RH
-
humid is the relative ambient humidity RH
in %.
[
RH = 80%
]
- TEMPER
-
tenv is the ambient temperature
[
Tenv = 20°C
]
Tenv
in
°C
.
- CEMTYP
-
cemtyp specifies the cement type:
[CEMTYP NR]
SL
for slowly hardening cements,
NR
for normal and rapidly hardening cements or
RS
for rapidly hardening high strength cements.
(file.dat)
'MATERIALS'
1 ...
CREEPN MC1990
YOUN28 30366.0
FCM28 28.0
H 40.0
LODAGE 28.0
7.4.2.2 ACI Code 209
The ACI209 code
descriptor indicates the creep function according to the
American Concrete Institute code 209 [1].
(syntax)
![\begin{figure}\centering
\begin{tabbing}
\texttt{'MATERI'}
\\ [-1.0ex]
\rule{14...
...texttt{CURTYP}\>\texttt{\textit{curtyp}}\(_{w}\,\){]} \end{tabbing} \end{figure}](img1340.png)
- YOUN28
-
e28 is the Young's Modulus of concrete (in MPa)
at the age of twenty-eight days.
DIANA determines the Young's Modulus at ages of loading from this value.
- H
-
notsiz is the notational size of the member h
in mm,
h = 2Ac/u
, with
Ac
the cross-section
and u
the perimeter in contact with the atmosphere.
- LODAGE
-
tlo is the concrete age
tlo
at loading in days.
[
tlo = 28
]
Determines the creep curve used for the generation of non-aging chains.
- AGING
-
indicates that aging chains must be generated:
tel is the concrete age
tel
in days
at the birth of the element.
[
tel = 1
]
- RH
-
humid is the relative ambient humidity RH
in %.
[
RH = 40%
]
- CEMTYP
- cemtyp
specifies the cement type:
I for class-I cement,
III for class-III cement.
[CEMTYP I]
- SLUMP
- slmm
is the slump of concrete slurry in mm.
[SLUMP 70]
- FINAGG
- agg
is the ratio of fine to total aggregate in %.
[FINAGG 60]
- AIRCNT
- air
is the air content in %.
[AIRCNT 7]
- CEMCNT
- cem
is the cement content in
kg/m3
.
[CEMCNT 450]
- CURTYP
- curtyp
specifies a curing method according to
the ACI 209 code [1]:
MOIST for moistening (the default) [MOIST]
or STEAM for curing with steam.
7.4.2.3 NEN 6720 Code
The NN6720 code
descriptor indicates the creep function according to the
Dutch NEN 6720 Code [76].
(syntax)
- YOUN28
-
e28 is the Young's Modulus of concrete (in MPa)
at the age of twenty-eight days.
DIANA determines the Young's Modulus at the age of
the loading from this value.
- FCK28
-
fck28 is the
characteristic strength
fck
(in MPa)
of concrete at the age of twenty-eight days.
Rule of thumb:
fck = fcm - 8
,
with
fcm
the mean compressive strength (in MPa) of
concrete at the age of twenty-eight days.
- H
-
notsiz is the notational size of the member h
in mm,
h = 2Ac/u
, with
Ac
the cross-section
and u
the perimeter in contact with the atmosphere.
- LODAGE
-
tlo is the concrete age
tlo
at loading in days.
[
tlo = 28
]
Determines the creep curve used for the generation of non-aging chains.
- RH
-
humid is the relative ambient humidity RH
in %.
[
RH = 80%
]
- CEMTYP
-
cemtyp specifies the cement type for specific codes:
A
for A-class cement,
B
for B-class cement or
C
for C-class cement.
[CEMTYP A]
Aging.
The standard NEN 6720 creep model can be written like
Equation (19.36) with
= 1
for no aging.
To include aging in the NEN 6720 model you may specify some data
items instead of the LODAGE item as specified above.
However, in doing so, you should realize that the creep model does no longer
conform to the original NEN 6720 model.
(syntax)
Input parameters are the same as for the standard NEN 6720 creep model
as described above, except for the following parameters which
replace the specification of the concrete age at loading.
- AGING
-
indicates that aging chains must be generated where tel
is the concrete age
tel
in days at the birth
of the element. [
tel = 1
]
- AGTIME
-
ta1 ...tan are the element ages for which
the aging coefficients are specified.
- AGINGF
-
be1 ...ben
are the aging coefficients
, where be1 is the
value of 
at element age ta1 etc.
7.4.2.4 User-supplied Creep Model
Via the USRCRP input data item and the user-supplied subroutine
USRCRP you may specify a customized creep function.
(syntax)
- USRCRP
-
specifies that the creep function
is determined via a user-supplied subroutine USRCRP
[§11.1.4].
DIANA passes the keyword usrkey to the first argument of this
subroutine.
- YOUN28
-
e28 is the Young's Modulus of concrete (in MPa)
at the age of twenty-eight days.
DIANA determines the Young's Modulus at the age of
the loading from this value.
- LODAGE
-
tlo is the concrete age
tlo
at loading in days.
[
tlo = 28
]
Determines the creep curve used for the generation of non-aging chains.
- AGING
-
indicates that aging chains must be generated:
tel is the concrete age
tel
in days
at the birth of the element.
[
tel = 1
]
Next: 8. Creep and Shrinkage
Up: 7.4 Determination of Chain
Previous: 7.4.1 Discrete Function
Contents
Index
DIANA-9.3 User's Manual - Material Library
First ed.
Copyright (c) 2008 by TNO DIANA BV.
![\begin{figure}\centering
\begin{tabbing}
\texttt{'MATERI'}
\\ [-1.0ex]
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...}
\\ [.5ex]
\>\>\(\cdots\;\)\>\emph{input parameters} \end{tabbing} \end{figure}](img1338.png)
![\begin{figure}\centering
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![\begin{figure}\centering
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![\begin{figure}\centering
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![\begin{figure}\centering
\begin{tabbing}
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