Kawama, Itsuo

Ohuchi, Hajime

Tsunokake, Hisao

Osaka City University Repository

Mem. Fac. Eng., Osaka City Univ., Vol. 49, pp. 59-65 (2008)
Fatigue Characteristic of Reinforced Concrete Member in Mineral Oil
Hisao Tsunokake*, Hajime Ohuchi** and Itsuo Kawama***
(Received September 30, 2008)
Synopsis
The present paper describes flexural shear cyclic loading test results of reinforced concrete member in mineral oil,
with focusing on fatigue characteristic due to liquid permeation into cracks of the member. In case of no fatigue
failure reached, monotonic load was again applied up to failure after cyclic loading. For comparison, similar
loading tests were also conducted in water and no liquid (n01111al) conditions. Cyclic loading and liquid
dependent failure behavior, i.e. crack progress, stiffuess reduction and displacement increase are discussed.
KEYWORDS: Fatigue, Reinforced Concrete Member, Flexural shear, Mineral oil penneation.
1. INTRODUCTION
In recent years, deterioration has been found in the concrete foundation for pressing machine of steel
production factory. In these facilities, circumferential temperature reaches up to 40 to 50 C degree around the
concrete foundation. As the result, accelerated evaporation of entrained water provides negative pressure and
leads absorption of mineral oil into concrete. In addition, repeated cyclic load is applied during n01111al operation.
These facts suggest fatigue orient deterioration of concrete. Chemical attack by plant oil has been well known,
but not by mineral oil. Rain water dependent deterioration of concrete slab subjected to repeated vehicle load is
also well known.
As the first step, authors conducted compressive fatigue test with concrete cylinders in the three different
circumstances, i.e. in mineral oil, in water and in no liquid, i.e. normal condition. Focusing points are load cycle
and liquid dependent strength and hysteretic stress strain relationship [1]. However significant effect of liquid
penneation into cracks was not observed. One of causes was that micro crack provided insufficient penneation
of more viscous mineral oil.
In these backgrow1ds, fatigue loading test has been conducted focusing on flexural shear fatigue
characteristic of reinforced concrete member. Test specimens designed as post yielding shear failure, are
similarly in the three different circumstances, i.e. in water, mineral oil and normal (no liquid) conditions.
Focusing points are load cycle and liquid type dependent crack progress, load displacement characteristic and
residual displacement increase. In case of no fatigue failure reached, monotonic load is again applied up to the
ultimate after fatigue test.
* Research Associate, Depmiment of Civil Engineering
** Professor, Department of Civil Engineering
*** General Manager, Nikken Sekkei Civil Engineering Co.
-59-
2. EXPERIMENTAL TEST
Concrete Reinforcement
f' Ee vc f sy E: sv Es f sue
(MPa) (GPa) (MPa) (11) (GPa) (MPa)
28.8 25.8 0.191 372.7 2165 172.2 515.1
120 150
DlO(SD295)
Photo 1 Test Specimen Set Up
Table 1 Material Properties
Table 2 List of Test Specimens
1000
-':;:'-30
0: Strain Gauge ®: Disp. Transducer I [Unit: mm]
Fig.l Specimen Dimension and measurement
:60· 150
Specimen
Test Condition Age Obtained Essential Yield Load (kN)
Circumferentional Applied Load (day) [Applied Upper and Lower Load Ratio (%) I
N-O Monotonic 70 16.7
N-I
o Liquid ~
N-2 Cyclic ~ (l0~80]
N-3 156
0-0 Monotonic 112 15.8
0-1 113
-
0-2 Oil 127
Cyclic - (I 0~80]
0-3 170
-
0-4 225
W-O Monotonic 102 16.0
W-I
Water
106
-
W-2 Cyclic ~ (lO~801
W-3 163
2.1 Test Specimens
As illustrated in Fig.l, test specimen has
dimension of Bl20mmxHl501llin xLlOOOmm,
shear span ratio of 3.75 and has single tensile
reinforcement allocated with no shear
reinforcement. As for specimen production,
once work form removal, one day after the
concrete placement, test specimens were sprayed
water cured during 28 days in the curing room
under 20 iJ temperature. Material properties are
illustrated in Table 1.
2.2 Test Procedures
Three points loading is illustrated
in Fig.1. Measurements are relative
displacement between loaded and
supported points, reinforcement
strains at three points from center at
l50mm distance and concrete
strains at both sides of loading
point.
Test variable is circumferential
condition, in mineral oil, in water
and no liquid. As illustrated in
Photo 1, a part of test specimen
where crack distributes is soaked in
the liquid. Test specimens are listed
111 Table 2, where for each
circumferential condition; one is for
essential monotonic loading while
another three or four are for cyclic
loading test. Essential monotonic
loading specimen is referenced for upper and lower load limit
of the cyclic loading test. 10% of yield strength obtained in
that essential loading test will be utilized as lower limit and
80% of that as upper limit for the following cyclic loading
test.
In the fatigue test, controlled load was sine wave with
0.5Hz velocity due to applied load capacity and provided
displacement. Because of rather slow velocity controlled,
250,000 load cycles was employed as a maximum number
except 0-4 specimen. If no failure reached in the fatigue test,
it was again monotonically loaded up to failure after 250,000
cyclic loading experienced. It is noted that 0-4 specimen
was additionally tested for potential fatigue shear failure (failed in shear at 461,000 cycles during cyclic loading).
-60-
3. FAILURE BEHAVIOR IN THE ESSENTIAL MONOTONIC LOADING TEST
II Oil: 0-0 II
a
c:
25
20
stage I
stage2
stage]
-No Liquid: N-O
-Oil:O-O
Water: WoO
o max. load
X faiJLu'e
-500
,
,
I~Q
: X
-JOOO
Fig.3 Crack Distribution
E[~]
Fig.4 Load-Strain Relationship
[Oil: 0-01
- stage I(before yield)
- stagc2(until max.)
stage3 (post ma:x.)
Ore-bar yiel d
o max. load
X lailure
o ]0 20 30
Fig.2 Load-Displace.me~t Relationship
5
o
JO
15
20
25
-1500
~I0:'1
I
Fig.2 illustrates load-displacement relationship
in the essential monotonic loading test specimens
for tlu'ee circumferential conditions and Fig.3
represents crack distribution in the mineral oil
specimen. There is no significant difference in
yielding and maximum load capacity between three
circumferential conditions. Also conunonly
observed in tlu'ee specimens was flexural crack
progress up to diagonal shear through out the
loading point in the ultimate stage. There is some
difference in the failure displacement between
three specimens due to flexural shear crack
propagation, where shear crack in the water and
mineral oil specimen progresses up to the right side
of bearing plate, while that in the no liquid
speCImen progresses up undemeath the loading
plate.
Fig.4 represents load strain relationship of
concrete at compressive flange, in which loading
history is respectively provided as stage I before
yielding, stage 2 before maximum loading and
stage 3 after that. In the stage I, compressive
strain, mainly due to flexural compression,
increases more due to dominant flexural cracks,
while in the stage 2, less due to predominance of
diagonal shear crack. In the stage 3, this
compressive strain decreases 111 the load
descending branch because of ultimate shear
failure, no flexural defonnation increase.
Although shear to flexural strength ratio of 1.37,
these specimens ultimately failed in flexural shear
and experimental maximum loads reached up to
around the calculated shear strength due to strain
hardening of reinforcement.
4. FATIGUE TEST
4.1 Failure Behavior in the Cyclic Loading Test
Experimental test results are sWllinarized in the Table 3 including essential monotonic loading test specimens.
Among them, water specimens W-2 and W-3 and mineral oil specimen 0-4 were failed in shear during cyclic
loading. The cyclic nW11ber at failure is shown in the parentheses of the table. Other test specimens were failed
in post yielding shear during final monotonic loading stage after cyclic loading application. The yielding load
-61-
Table 3 Summary of Test Results
.'11'
"'I' ('1/' ,'rJl />111 ,,\/, Ip nl L't" 0:\/1 R II/"'!J//? //(1 L"P
Applied Load
Failure i\ludeSpecimen P,., PI·,"I/IIP I'll PIli /) III "'I' /P II/} II",
Cyclic Monotonic
N-O 16.6 - 19.4 - - 0.0558 1.00 0
N-I 16.5 099 21.4 1.10 - 0.0638 1.14 0 0
N-2 17.6 1.06 18.8 0.97 - 0.0402 0.72 0 0
N-3 0.0620 1.11 0 0 Post Flexural16.7 1.01 18.7 0.96 - Yeilding Shear
0-0 16.3 - 19.0 - - 0.0429 1.00 0 Failure
0-1 17.4 1.07 20.7 1.09 - 0.0747 1.74 0 0
0-2 17.3 1.06 19.3 1.02 - 0.0347 0.81 0 0
0-3 17.1 1.05 18.1 0.95 - 0.0509 l.J9 0 0
0-4 12.6 0.67 0.68 0.0080 0.19 0(461,152) - Shear Failure During- - Fatigue loading
WoO 160 - 18.8 - - 0.0453 100 - 0 ' v, oe."" ,
0.83 0 0
Ycilding Shear
W-I 17.6 1.10 181 096 00376 , ,:I ....
W-2 - - 12.8 0.68 0.69 00066 0.15 0(25,280) . Shear Fnilure During
W·3 - - 12.8 0.68 0.69 0.0147 0.32 0(32.807) - Fatigue londing
Note: P "j exp : yeilding strength, P '"~ exp : maximum experimental strength, P V" cal: estimated strength, R '"~ exp : ulrimme rotation
For Oil, R ,,4 exp : rotation of 461,000 cycle
For Water, R ,,2 exp and R ,,3 exp : rotation of25,000 cycle and 32,000 cycle respectively
-I
100
11101111
20000
2S0UIIo(mm)
14 Oil : 0-2
j ,
12 I , 12
/1' 10 10,
3' , ~'-I ,, 2:: ,-I
"- 6100 ... 100
!OOOO 10000
250000 2S0000,
.,
.J 0 0
0 0
o(mm) o(mm)
Fig.S Load-Displacement History
o
o
141- ..-'
12
10
Nu l.iquid : 1\-2 14
lOll : 0-21 14 IWaler: W-21 14
-I
-I -I
11111 , \
, \ 12 100····100 \.~~,1111100 1110110 1110110Z 2SIIOO11 2S0000 3' 2110110~ ~ 250110"- 2::
0 0 II
-1000 ·SOO 500
-1000 -500 0 500 -1000 -500 500d~) d~) d~)
Fig.6 Load-Strain History
ratio which is defined as the yield capacity at cyclic loading divided by that at essential monotonic loading,
provides no significant effect of fatigue deterioration except above mentioned two water specimens,
Fig.S and Fig.6 represent displacement and concrete strain histories of the cyclic loading test specimen
respectively for each circwnferential condition, And crack distribution until 1,000th cyclic loading, the end of
cyclic loading and post fatigue monotonic loading is respectively illustrated in Fig.7, where in the water specimen
W-2 failed in shear, crack distribution is shown until cyclic loading number of 25,000. It is noted that in the
Fig.S and Fig.6, the 1st cycle history is affected by cracking because applied upper limit load is more than the
flexural tensile strength of the member. Fig.S suggests cyclic nwnber dependent increase of displacement, where
in the water specimens failed during cyclic load application, larger displacement reached even at lO,OOOth and
displacement at 20,OOOth is larger than that at 250,OOOth of both mineral oil and no liquid specimens.
-62-
- - 1,OOOcycleOil: 0-2
Water: W-2
II No Liquid: A-2 11 1 - -I ,~OOcycle
....._ -2),OOOOcycle
../ \ ". Post I'aligllc
_______________ -If------- \lk- ~un~l~'~~ ~~"d~'~
~ L
i - -1,OOOcycle
~=====~-~,.~._~-11 -25.000cycl·
~---------------f----1- --'\:~~::
II i~=====:!J~7"_..!c-~1 -25,OOOOcycle
,;:Y _~ Posl ~dllgller MonotonIc 1Odt!tn U
------------~------- ----------- - - - -
Fig.7 Comparison of Crack Distribution
specimen.
As for the strain history at compressive concrete flange shown
in Fig.6, it seems to cOlTespond with displacement history except
water specimen where strain at 10,000th cycle is smaller that that
at J OOth, and cyclic number dependent decreases is observed for
further cycles. This strain decrease phenomena of the water
specimen is explained by significant shear defoD11ation increase
and flexural stress release as a result at the progressive shear
failure stage. It is noted that for no liquid specimen, predicted
design fatigue strength [2] defined below eq.(l) provides 9.46kN at 250,000 cycles (13.4kN as upper load applied
in the present test), that means all specimens are predicted as possible fatigue failure during cyclic loading stage.
Fig.7 suggests that in comparison between no liquid and
mineral oil specimens, flexural crack followed by flexural shear
crack is similarly observed, however flexural shear crack of the
water specimen distributes up at earlier stage. In the water
specimen, it distributes much earlier, say at around 10,000th cycle,
up to as same extent of that at 250,000th cycle of the mineral oil
Vrcd=Vcd (1- VpdIVcd) (l-logN/ll)
V rcd : Fatigue shear strength V cd : Shear strength
Vpd : Applied shear force N : Fatigue life(Load cycles)
(1)
4.2 Displacement History
Fig.8 provides load cycle dependent stiffness reduction, where the stiffness is defined as load amplitude divided
by responded displacement amplitude for each loading cycle and stiffness ratio defined as the prescribed stiffness
divided by initial stiffness at the first loading cycle. Each specimen provides significant reduction of stiffness,
however after 10th cycle, some difference is observed due to circumferential condition. In the no liquid
specimen, stiffness ratio gradually decreases until 1,000 load cycles but is rather stable after that. In contrast,
both water and mineral oil specimens continuously decrease even after that cycle. However in the shear failed
specimens, two water specimens W-2 and W-3 and the mineral oil specimen 0-4, the history does not provide
sudden reduction even toward shear failure.
..
....
I.
~N-I
11111
------- N-2
---"-N-3
911 !-+-O-l
-?6--0-2
~ XII0 --k-- ()_.~
0 711
;;:;
0::: (lO
'"v;
<[)
.c ~()
c;::::
a
.11
'II
20
III 100 1111111 11111110 111110011 10000011 1110 1000 10000 100000 1000000
Load cycle No.
Fil!:.8 Load Cycle Dependent Stiffness Ratio
Load Cycle No.
Fil!:.9 Load Cycle Dependent Displacement
-63-
Fig.9 provides load cycle dependent displacement response, where drift angle is defined as the displacement at
each cycle upper load divided by shear span L=450mm. No liquid (nol111al) specimens tend to increase linearly,
while water specimens provide similar increase until around 4000 cycles, but provide significant incTease after
that cycle except W-I with no shear failure reached. Among mineral oil specimens shown as thick solid line,
0-4 specimen provides significant increase after 400,000 cycles and others some increase after 100,000 cycles.
4.3 Damage Potential with Liquid Pressure
Two of three water specimens provided shear failure during cyclic load application, while one of four mineral
oil specimens shear failure. In general, with liquid existence, crack especially flexural shear crack tends to be
enhanced. That enhancement is more in water than in mineral oil with higher viscosity. In the eye observation,
both at water and mineral oil specimens test, paste was pushed out of existing cracks and flew out in the acryl
storage with increase of load cycles. However more amolU1t of paste flow out was observed in the water specimen
than mineral oil specimen. This fact suggests difference of liquid pem1eation and pressure dependent 011 liquid
viscosity.
Fig.l0 Load Displacement Relationship after
Fatigue Load Experienced
4.4 Post Fatigue Monotonic Loading Test
Monotonic load was applied up to failure for survived
specimens. Obtained load displacement relationship is
represented in Fig.l0 where the results of same
specimens is provided for no liquid and mineral oil
condition, and the result of W-I specimen provided for
water. With some difference in maximlU11 load capacity
and ultimate displacement, it is commonly said that load
increases up to 17-18kN at yielding and after that
displacement increases until ultimate shear failure. As
shown in Fig.7 some flexural shear cracks were
distributed but no flexural yielding was reached.
Flexural shear crack enhanced during cyclic load
application, progressed toward the compressive flange
section.
25
20
15
~
Co..
10
5
0
0 5 10 15
o[mm]
X Failw'e
£'; Yeilding I'oinl
4.5 Ultimate Strength and Ultimate Displacement
Obtained ultimate strength and ultimate displacement is respectively summarized in Fig.ll and Fig.12. Fig.ll
provides no significant difference in ultimate strength except liquid specimens failed in shear during cyclic load
=2
=4
_3
=0
=1
.-
WaterOilNo Liquid
'I ~.'\\'L.orl'ycliL
~ 1.0 i.ld ill g
L.t.Oo'---'-__"-_.Ll>:>J..-l.-Uo:::=1I'-'--"",,-,-!_Il..L-..J
0.08
0.01
0.00
0.02
0.07
0.06
"0
J; 0.05
"~ 004
-<
a:: 0.03~
--*- Ave. orCyclic
Loading
WaterOilNo Liquid
\:
5
o
25
20
z
-"~5
'"o
....l
",10
'"~
Fig.ll Comparison of Ultimate Strength Fig.12 Comparison of Ultimate Displacement
-64-
application. Shear strength of these latter two water specimens provide 69% of calculated value, further less
compared with obtained flexural strength in other specimens, where averaged value is provided only for post
yielding shear failure specimens.
Fig.12 provides ultimate displacement, where some difference is observed between specimens because all of
them were ultimately failed in shear; i.e. some of them in shear during fatigue loading and most of them in
flexural shear. In general, mineral oil specimens provide less value than no liquid (non11al) specimens and water
specimens least value among all specimens failed in flexural shear.
5. Concluding Remarks
Cyclic loading test has been carried out in order to study liquid penneation dependent fatigue characteristic of
reinforced concrete beam. Obtained results are concluded as followings.
1) Flexural shear crack develops during cyclic load application.
2) Load cycle dependent displacement increases more in water and the next, mineral oil than normal(no liquid)
condition, and two of three specimens in water and one of four those in mineral oil failed in shear during cyclic
loading.
3) In the post fatigue monotonic loading test, observed is post flexural yielding shear failure at ultimate.
4) Displacement ductility decreases more in water and the next, mineral oil than nonnal conditions.
5) For practical design of reinforced concrete member with mineral oil pen11eation, it seems to be conservatively
designed with fatigue strength predicted by cunent design standard considering water penneation.
REFERENCES
[1] M.Itoh, LKawama, H.Tsunokake and H.Ohuchi: A Study on Compression Fatigue Characteristics of Concrete
in Mineral Oil, Proceeding of JCI, Vo1.29, pp.849-854 (2007)
[2] JSCE: Standard Specification for Concrete Structures (2002)
-65-


Fatigue Characteristic of Reinforced Concrete Member in Mineral Oil

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Fatigue Characteristic of Reinforced Concrete Member in Mineral Oil

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