Civil Engineering Reference
In-Depth Information
after loading,
D
=
0.486, which is close to
D
cr
=
0.5, indicating that the
cracking load
N
cr
is almost reached.
•
As the strain of IGNA (
2
) increases with the loading magnitude, the
FCR increases gradually with the increase of
D
. This provides convinc-
ing evidence that the suggested formula
Y
ε
=
m
exp(
−
X
/
n
)
+
p
effectively
meets the relationship between
ε
2
and FCR.
•
The absolute value of the displacement of IGNA (
y
0
) increases gradu-
ally with increased absolute values of FCR and
D
.
˜
1
and
˜
3
,
•
Other factors such as
σ
σ
ε
1
and
ε
3
increase with an increase in
FCR and
D
.
4.7 Conclusions
A large number of experimental investigations have been carried out on
the workability, electric properties and mechanical behaviour of concrete
containing conductive materials. The effects of NCB, CF and diphasic BF
on the relationship between fractional change in resistance, strain and
degree of damage prior to cracking have been analysed. A relationship
between the FCR and the strain of IGNA (
ε
2
) is suggested. The results have
led to the following conclusions:
1. Concrete conductivity increases with an increase in dosages of NCB
and CF. However, the workability of fresh concrete is an important
precondition for selecting the types and content of the conductive
materials.
2. Workability declines with an increase in NCB or CF content and the
upper limit of conductive materials is determined mainly by workability,
not by conductivity. This point had not been taken into consideration
in previous investigations.
3. The fl exural strength of a beam usually increases with an increase in
CF and BF content. However, only the addition of NCB exerts any
infl uence on the fl exural strength.
4.
The strain of IGNA (
2
) is a function of FCR. Prior to the concrete
cracking, the First Order Exponential Decay function agrees well with
the relationship between
ε
ε
2
and |FCR| during the loading process of
CFRC beams.
5.
Both the degree of damage (
D
) and the strain of IGNA (
ε
2
) increase
with an increase in FCR.
6. All the mechanical factors in concrete containing conductive admix-
tures decline with an increase in FCR and
D
.
7.
Results from examples evaluating the effect of diphasic electric conduc-
tive materials on the capacity for the self-diagnosis of strain and damage
have been validated.
Search WWH ::
Custom Search