A
1 Advanc (zhdzhy 2 Profess 3 Profess 4 Enginee 5 Advanc 6 Advanc ABSTRA P the main LOCA a be embe test the s monitor monitori and prov audio str stability CONCR S these mo loading a strain. GL2000 G as follow 28
ANALYSI
Hui ce Engineer, [email protected]) sor, Central R sor, Central R er, Central R ce Engineer, ce Engineer,ACT
Prestressed co n function of accident happ dded in the c strain data in the day-to-ing strain dat vide valuable
rain gauges of strain gau
RETE SHRI
Several mode odels have t age and othe
Model of Co
Gardner and L ws:
0 ( ( 2 t t t tc
ISOF OF
FOR
idong Zhang Central Rese ) Research Inst Research Inst Research Insti Central Rese Central Rese oncrete conta containment pening. In or concrete to m n the process -day concret ta play a key e data for thhave relatio uge, shrinkag
INKAGE, CR
els of concret their own ch er factors. GL
oncrete Cree Locktnan pro 3 . 0 0 3 . 0 0 14 ) ) t
If to
CONCRE
R CONTA
g1, Songtao L Haixian
earch Institut
titute of Build titute of Build itute of Build earch Institut earch Institut
ainment stru t is to protect
der to evalua measure the s
of regular st te strain to
role to evalu e researching on with work ge and creep o
REEP MOD
te creep and haracteristics, L2000 model
ep and Shrin
oposed the G
0 5 . 0 ( ) 7 ( t t t to If c t ,
tc
ETE STR
AINMENT
Lin2,Yonghu ng Xu5, Jibin
te of Building
ding and Con ding and Con ding and Con te of Building te of Building
cture is a spe t the reactor ate the contai
train, one asp trength test o
determine t uate the statu
g of prestres king conditio of concrete, e
DEL AND F
shrinkage ar , involving t l is popular u
nkage
GL2000 mode
0.5
0 0 2 ) 7 t c o t t
,
tc( 1 t to c
RAIN LAT
T STRUC
uan Wang3, ng Zhang6
g and Constr
nstruction CO nstruction CO nstruction CO
g and Constr g and Constr
ecial structur and contain r inment struct pect, these au of the contain
the status o us and life ext ssed concrete on of the co environment
ORMULA
re ACI209, C temperature used for pred
el in 1999. C
1.086 1
( 5 . 2
1 c ) / ( 15 . 0 s v t to cTE DEVE
CTURE
Zhengfeng ruction CO.,L O.,LTD.MCC O.,LTD.MCC O.,LTD.MCC ruction CO.,L ruction CO.,Lre form in nu radioactive m ture, the aud udio strain g nment structu of the conta tension of th e structure. T ontainment s
of using.
CEB-FIP MC and humidit dicting the de
Concrete creep 2 )( t t h o 5 . 0 5 . 0 2) )
ELOPMEN
Song4,
LTD.MCC G C Group C Group C Group LTD.MCC G LTD.MCC G uclear power material prod dio strain gau auges would ure, another a ainment stru
e containmen The monitori
tructure, the
C90, B3, GL2 ty, scantling evelopment o p coefficient 2 ) / ( 15 . 0 s t t o
NT
Group Group Groupr plant, and duced when uges should d be used to aspect is to ucture. The
nt structure, ing data of e long-term
2000, SAK, s, concrete of concrete
t formula is
t is the concrete age period (day), tc is concrete drying instar (day), taking 15 days, to is
loading of concrete age period (day), taking 365 days,
v
/s
is ratio of volume and surface area, h is relative humidity (decimal).GL2000 about plain concrete shrinkage formula:
sh
shu
(h)
(t) (2) 418 . 1 1 )
(h h
6 5 . 0
10 30
1000
cm shu
f k
5 . 0
2 ) / ( 15 . 0 )
(
s v t
t
t t t
c c
Which k is relate to the type of cement, ordinary portland cement to take 1, fcman average concrete cube strength of 28 days.
DEVELOPMENT OF CONCRETE MONITORING STRAIN OF A NUCLEAR POWER PLANT CONTAINMENT
The containment of one nuclear power plate is composed of raft foundation, the cylinder concrete wall, hemispherical dome. The inner diameter of the cylinder is 44.0m, and the thickness of concrete wall is 1.2 m, height 41.6m, the section shape of prestressing concrete containment shown in figure 1. The structure of the containment is prestressed reinforce concrete structure. The mix proportion of cement, sand, gravel, fly ash, water was 1, 1.62, 2.52, 0.14, 0.46, and the 28 days compression strength of concrete was 61.2MPa.
Figure1. Section of concrete containment
Development of Radial (Thickness) Direction Monitoring Strain in Containment Wall
The pre-stress of concrete of containment along vertical and ring directions have been set up through stretching of steel strands distributed in the two directions, and the concrete tensile strain would be produced along the thickness direction (radial), and the data of tensile was very small, especially in the junction field of the buttress of containment and raft foundation, the monitoring data of strain gauges were almost zero during the construction of prestressing. The curves of data of long-term monitoring strain and concrete temperature are shown in figure 2. From the analysis of monitoring data of concrete strain, the concrete tensile strain has changed to compression strain. But, in fact, the stress established in the radial direction of the wall is still tensile. This phenomenon is the result of shrinkage and creep of the concrete. The curve of theory of strain in the figure 2 is got from GL2000 model, including creep and shrinkage of concrete.
The trend of convergence of curve of GL2000 is obvious following the time development, but the actual monitoring curve of strain is still not obvious signs of convergence after 2500 days (about 7 years) of the establishment of prestressing.
0 500 1000 1500 2000 2500 3000 5
10 15 20 25 30
35 0 500 1000 1500 2000 2500 3000
-80 -60 -40 -20 0 20
Tem(
oC）
Time(day)
Temperature monitoring curve
Str
ain(10
-6 ) monitoring of concrete straintheory strain curve of GL2000
reactor start-up
Figure 2. The theory curve and the monitoring curve of concrete strain and temperature (Buttress root)
0 500 1000 1500 2000 2500 3000
10 15 20 25 30 35
40 0 500 1000 1500 2000 2500 3000
-20 0 20 40 60 80
Tem(
o C)
Time(day）
curve of temperature
Str
ain(
10
-6 )
curve of monitoring strain
Establishment of prestressing
Figure 3. The monitoring curve of concrete radial direction strain and temperature in the wall
Development of Circumferential Strain of Concrete Containment
The value of compressing strain is relative larger than vertical direction on the concrete in the wall of containment. The average monitoring data of concrete strain and temperature of the inner side of wall, see figure 4. And the monitoring curve of outer side of the wall, see figure 5.
0 500 1000 1500 2000 2500 3000 10
15 20 25 30 35
40 0 500 1000 1500 2000 2500 3000 -800
-700 -600 -500 -400 -300 -200 -100 0
Tem(
o C)
Time(day）
curve of temperature
Strain(10
-6 ) curve of monitoring strain
Theory curve(GL2000)
establishment of prestressing
Figure 4. The monitoring curve of tangential
direction strain and temperature in the inner side of concrete wall
0 500 1000 1500 2000 2500 3000 10
15 20 25 30 35
40 0 500 1000 1500 2000 2500 3000
-500 -400 -300 -200 -100 0
Tem(
o C)
Time(day)
curve of temperature
Strain(10
-6 )
monitoring strain
theory of creep and shrinkage
establishment of prestressing
Figure 5. The monitoring curve of tangential
direction strain and temperature in the outer side of concrete wall
Development of Vertical Strain of Concrete Containment
Brief Su B fluctuatio recovera will mak
W some dri pattern o produce lower fre
verti
verti
ummary of C Because of c on with the c able, the resid ke some contr With the Lon ift, because o of steel strin
a certain slip equency of th
F ical direction
10 15 20 25 30 35 40 -300 -250 -200 -150 -100 -50 0
Te
m(
o C)
S
trai
n(10
-6 )
F ical direction
Concrete Stra constraint imp
change of tem dual thermal ribution to th ng-term usin of the metho g and ancho pping from th he steel string
igure6. The m n strain and te
0 500
0 500
establishment o
igure7. The m n strain and te
ain Monitorin posing on the mperature. Te strain will b he total strain ng, these aud od of machin oring disc in he anchoring g. The reduc
monitoring c emperature in
0 1000
0 1000
Tim
monitori theory o
of prestresing
monitoring c emperature in
ng Data in C e containmen emperature s be produced, n.
io strain gau ning process the strain g g under the lo
e of reading
curve of conc n the outer si
1500 20
1500 20
me(day)
curve o ing strain of of cocrete cr
curve of conc n the outer si
Containment nt, monitorin stress and stra
, with no rec
uges having e and material auge is impo ong-term usin value of sen
crete
ide of concre
000 2500 000 2500
of temperatur f concrete reep and shri
crete
ide of concre
t
ng strain of co ain causing b covery, accum
embedded in l properties o ortant, becau ng. These ph sor will resu
ete wall
3000 3000
re inkage
ete wall
oncrete prese by temperatu mulating resi
n the concrete of sensor. Th use the steel henomenon w lt compressio
ents regular ure of is not idual strain
e, there are he occlusal string will will leads to
increase, even more than the true strain because of concrete shrinkage, creep, temperature accumulation generated value, conceal the truth.
The empirical formula and prediction model of concrete shrinkage and creep, were popularly got basing on laboratory conditions (constant temperature and humidity, small size of component), and these conditions have difference with the actual environment, and certain specific conditions in practical projects may guide the development of concrete shrinkage and creep. So the job of researching and measuring for the shrinkage and creep of concrete is needed.
Containment is a prestressed concrete structure, and the concrete material has nonlinear property under the temperature and stress. Along with the time development, shrinkage and creep of concrete, relaxation of prestressed reinforcement, would cause stress redistribution on the concrete. Seasonal change of air temperature, concrete shrinkage, creep and prestress steel relaxation and differences between sensor and concrete thermal parameters, together, result the development of the monitoring compressing strain.
CONCLUSION
There is still a large development of concrete shrinkage and creep after seven years in Large size prestressed concrete members, is not negligible. The actual monitoring data deviates from the theoretical value.
Temperature stress and strain caused by temperature changes have certain amount of unrecoverable, and residual temperature strain is to make some contribution to concrete strain the total.
The predictive models of concrete creep and shrinkage are based on idealized conditions, under the conditions of lab, there are great differences with the actual environment. And the influencing factors are not comprehensive, even some special factors are ignored.
These predictive models need further researching and revising, and should base on the monitoring data more than 3 years.
REFERENCES
Bazant Z.P.(2000).Criteria for Rational Prediction of Creep and Shrinkage of Concrete, in:A.AI-Mannerseer ed.,A. Neville Symposium:Creep and Shrinkage Structural Design Effects,ACI Fall Convention,1997,ACI SP-194,pp.237-260.
