understanding of concrete structure: multi-scale ...multi-scale/maruyama.pdf · understanding of...

Ippei MARUYAMA, NAGOYA UNIV.

UNDERSTANDING OF CONCRETE STRUCTURE: MULTI-SCALE OBSERVATIONS AND MODELING IPPEI MARUYAMA NAGOYA UNIV. SYSTEMIZATION OF CONCRETE SCIENCE AND TECHNOLOGY THROUGH MULTI-SCALE MODELING 13RD JULY, 2015

1


MULTI-SCALE PROBLEM • Long-term service of concrete structures is required by many

reasons. (Economical, Environmental (CO2, saving materials))

• Maintenance / Aging management is required.

• The knowledge of Maintenance / Aging management should contribute to the design of new structures.

• In matured society, extension of service life of concrete structure is more important rather than re-build the structures. Especially in case of Japan, which is under decreasing in population.

• Sensing and monitoring are applied to many structures for evaluating structural performance, damage or deterioration of reinforced concrete members.

2


NEW PROBLEM OBSERVED IN MONITORING : ONAGAWA NPP

Onagawa NPP-3 was suffered from several (relatively large) earthquakes. Based on the monitoring results of accelerometer or velocimeter, modes of vibration are evaluated and natural frequencies were obtained.

Even though, all the earthquakes were found that they did not affect the structural cracking of quake resisting walls according to the design basis evaluation, 1st mode natural frequency of structure was decreased.

0 2 4 6 8 100

0.2

0.4

0.6

0.8

1

Rel

ativ

e na

tura

l fre

quen

cy (T

/To)

Years after constructionSimulation results of nuclear power plant building 2 and 3 in Onagawa site of Tohoku electric power company, Nuclear and Industrial Safety Agency Japan, 2011 (in Japanese). 3


NEW PROBLEM OBSERVED IN MONITORING : 8-STORY BRI BLDG

Building Research Institute, they have 8-story steel-reinforced concrete building. It contains many kinds of monitoring system and using the monitoring data, the change in natural frequency has been detected.

The trend is very similar to that of Onagawa NPP-3.

0 2 4 6 8 100

0.2

0.4

0.6

0.8

1

Rel

ativ

e na

tura

l fre

quen

cy (T

/To)

Years after construction

Onagawa-1 NPP BLI-building

T. Kashima, Y. Kitagawa, Dynamic characteristics of a building estimated from strong motion records using evolution strategy, J. Struct. Const. Eng. AIJ, 602 (2006) 4

Onagawa NPP-3


NEW PROBLEM OBSERVED IN MONITORING : 8-STORY BLDG

It is also confirmed that this decreasing trend is observed between earthquakes. During the every earthquakes, there is no damage, except for Tohoku-earthquake.

L. Li, A. Nakamura, T. Kashima, M. Teshigawara, EARTHQUAKE DAMAGE EVALUATION OF AN 8-STORY STEEL-REINFORCED CONCRETE BUILDING USING Sa-Sd CURVES, J Struct Constr Eng, 79 (2014) 1107-1115. 5


POSSIBLE IMPACT - For high-rise building, the decreasing of natural frequency

of building may cause to resonance, even wide range of frequency is considered in design state. System controlling is needed for compensating large seismic deformation.

- For nuclear power plant, supporting system is important. Resonance with piping system, cable system, or other facilities introduced in the plant are important issue. 2nd mode of structure might arise the problem. Aging management is important.

- Fundamental mechanism understanding and prediction is needed for aging management.

6


PASTE-AGGREGATE-CONCRETE

PASTE C-S-H, Mesoscale structural compaction

+ Dehydration of C-S-H from interlayer and

resultant strength change

Strength Shrinkage

Aggregate

Mineralogical composition

Shrinkage Stiffness, Strength

Damage in concrete

Concrete stiffness

Concrete shrinkage

Stiffness

Cracking in member

Stiffness of member 7


SHRINKAGE OF PASTE

8


IRREVERSIBLE SHRINKAGE

10

0 0.2 0.4 0.6 0.8 1-0.006

-0.005

-0.004

-0.003

-0.002

-0.001

0

Relative humidity (p/p0)

Stra

in (m

/m)

N55

I. Maruyama, Origin of Drying Shrinkage of Hardened Cement Paste: Hydration pressure, Journal of Advanced Concrete Technology, Vol. 8, No. 2, pp.187-200, 2010.6


MECHANISM OF SHRINKAGE IN FIRST DESORPTION

11

-0.016

-0.014

-0.012

-0.01

-0.008

-0.006

-0.004

-0.002

0

0 0.5 1 1.5 2

Shr

inka

ge s

train

(x10

-6)

Statistical thickness of adsorption (nm)

- Where disjoining pressure acts? - Long-term shrinkage is always liner function of statistical

thickness of adsorption.

0 0.2 0.4 0.6 0.8 1-0.006

-0.005

-0.004

-0.003

-0.002

-0.001

0

Relative humidity (p/p0)

Stra

in (m

/m)

N55

I. Maruyama, Origin of Drying Shrinkage of Hardened Cement Paste: Hydration pressure, Journal of Advanced Concrete Technology, Vol. 8, No. 2, pp.187-200, 2010.6


DIFFERENT SHRINKAGE WITH DIFFERENT PRE-DRYING

12

SDSXX: Slowly (more than 1 year ) Dried Sample at XX %RH.


DIFFERENT SHRINKAGE WITH DIFFERENT PRE-DRYING -Shrinkage of paste with different RH pre-drying showed different shrinkage strain = different irreversible shrinkage. - Shrinkage 40-98%RH shows good correlation with incremental statistical thickness of adsorption at 40-98% RH.

13

Maruyama, I., G. Igarashi and Y. Nishioka (2015). "Bimodal behavior of C-S-H interpreted from short-term length change and water vapor sorption isotherms of hardened cement paste." Cement and Concrete Research 73 0 158-168.


SHRINKAGE IN LOW RH AREA - Shrinkage strain under 40% RH is high correlation with water vapor BET surface area of hcp.

14

3l S

l Eρ σ∆ ⋅

= ⋅ ∆

S

Maruyama, I., G. Igarashi and Y. Nishioka (2015). "Bimodal behavior of C-S-H interpreted from short-term length change and water vapor sorption isotherms of hardened cement paste." Cement and Concrete Research 73 0 158-168.


15

Sorption potential contour

- From the 1H-NMR experiment, matured cement paste does not contain capillary water. (Muller et al.)

- In the interlayer, sorption potentials from both planes are overlapped. Sorption potential is higher in interlayer.

WHERE IS WATER?

1) Muller et al., The Journal of Physical Chemistry C, Vol.117, No.1, pp.403-412 (2013)

2) G. Igarashi, 2014, Behavior of Water Vapor Adsorption on Calcium Silicate Hydrate in Portland Cement Pastes, dissertation, Nagoya university.

*1

*2


TWO POSSIBILITY ～90％ RH

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A: Gel and constant layer disctance

B: Movable layer distance *2

Feldman model

2) Maruyama, I., G. Igarashi and Y. Nishioka (2015). "Bimodal behavior of C-S-H interpreted from short-term length change and water vapor sorption isotherms of hardened cement paste." Cement and Concrete Research 73 0 158-168.

1) R.F. Feldman, Sorption and length-Change scanning isotherms of methanol and water on hydrated portland cement in: Fifth international symposium on the chemistry of cement, Tokyo, 1968, pp. 53-66.

*1

3) G. Igarashi, 2014, Behavior of Water Vapor Adsorption on Calcium Silicate Hydrate in Portland Cement Pastes, dissertation, Nagoya university.

*3


SHRINKAGE OF AGGREGATE

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SILICIOUS AGGREGATE - Aggregate in concrete shows

considerable shrinkage and it affects on shrinkage of concrete (Roper, PCA, 1960) as well as other physical properties of concrete.

- Sedimentary silicious rocks are used in Japan, but they show wide range in properties.

- Various and typical rocks are investigated.

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Submitted to Construction and Building Materials


SHRINKAGE OF AGGREGATE - Short-term length- change isotherms with orthogonal 3-

directions were recorded.

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COMPONENTS OF AGGREGATE - Powder XRD / Rietveld analysis was conducted.

20



CORRELATION - Strong correlation is obtained between amount of chlorite

and shrinkage strain. - Weathering and resultant chlorite, not Illite or Sericite,

cause shrinkage in matrix, and produce macroscopic shrinkage of aggregate.

21



INTERACTION BETWEEN AGGREGATE AND MATRIX

22


DAMAGE IN CONCRETE - Heterogeneous behaver between coarse aggregate and

matrix must be observed. - Damage behavior is detected by Digital Image Correlation

Method (DICM).

23 Max. principle strain dist. Results of fluor-epoxy intrusion method

I.Maruyama,H.Sasano,Strain and crack distribution in concrete during drying,Materials and Structures,2014


DIFFERENCE IN SHRINKAGE

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I. Maruyama, O. Kontani, A. Ishizawa, M. Takizawa, O. Sato: Development of System for Evaluating Concrete Strength Deterioration Due to Radiation and Resultant Heat, 3rd International Conference on NPP Life Management for Long Term Operations, IAEA-CN-194-096, Salt Lake City, USA, 12-14 May 2012.


0 1 2 3 4 5 6 7 8 9-1500

-1000

-500

0

Drying period (days)

Dry

ing

shrin

kage

(µ)

ROLE OF COARSE AGGREGATE (1)

25

φ100mm

9 mm-thick

Mortor

Sandstone

Limestone LIMESTONE

SANDSTONE H. Sasano, N. Horiguchi, i. Maruyama, Evaluation of strain distribution and microcrack in concrete due to drying, Proceedings of Japan Concrete Institute, 34 (2012) 454-459.


SHRINKAGE OF CONCRETES - Concretes with different type of coarse aggregate is investigated. They are equilibrated with different drying condition.

26

I. Maruyama, H. Sasano, Y. Nishioka, G. Igarashi, Strength and Young's modulus change in concrete due to long-term drying and heating up to 90 °C, Cement and Concrete Research, 66 (2014) 48-63.


DAMAGES IN CONCRETE

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YOUNG’S MODULUS

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□G1：Limestone L. Sh. Gmax: 20 mm ■G2：Sandstone S Sh. Gmax: 20 mm ▽G3：Altared tuff. S. Sh. Gmax: 20 mm ▼G4：Altared tuff. S. Sh. Gmax 13 mm ○G5：River sand S. Sh. Gmax: 20mm

paste



MECHANISM

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Mortar / Concretes

Concrete

Mortar



MECHANISM

30

Cracked parts indicates the voids in concrete



DISCUSSION: ADDITIONAL DEFORMATION

31

εe

εcr,b

εcr,dry

Neville’s schematic figure Modified

εe

εcr ≈ εcr,dry

εe: is increased due to micro-cracking or reduction of Young’s modulus

εcr > εcr,b

ε ε

Time Time

εcr is incresed due to localized and stress re-distribution in concrete due to cracks


TEST BY DAVIS ET AL.

32

00.5

11.5

22.5

33.5

4

0.01 0.1 1 10 100

Cree

p c

oeff

icie

nt

Time under load (years)

Wet70%RH50%RH

0

0.5

1

1.5

2

2.5

3

3.5

100% RH 70% RH 50% RH

Cree

p co

effic

ient

Stress re-distributionYoung's modulus reductionFundamental

Localized and additional stress is produced in compression stress pass.

Averaged elastic impact of crack

Localized long-term impact of crack

1) E.D. Raymond, E.D. Harmer, Flow Of Concrete Under the Action of Sustained loads, Journal Proceedings, 27.

Ref 1)


VISIBLE AND INVISIBLE CRACKING

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CRACKING OF RC MEMBER

34

Restraint body (Ratio of area:38.5%) Strain gauge

Deformed rebar D10 (Reinforcement ratio : 0.5%) Unit : mm

Dry

ing

shrin

kage

(x10

-6)

Time after drying (days)

- Drying shrinkage induced cracking behavior of concrete showing different shrinkage strain is investigated.

- PL1: Large shrinkage (1100µ), PL2: Moderate shrinkage (950µ), and PL3 Low shrinkage: (750µ)

Y. Mitani, Y. Ishii, M. Tanimura, I. Maruyama, Quantitative evaluation on reduction effect of drying shrinkage cracks by expansive additive, in: AIJ (Ed.) Summaries of technical papers of annual meeting, Nagoya, Japan, 2012, pp. 747-748.


CRACKING OF RC MEMBER

35

Unit : mm

Dry

ing

shrin

kage

(x10

-6)

Time after drying (days)

Y. Mitani, Y. Ishii, M. Tanimura, I. Maruyama, Quantitative evaluation on reduction effect of drying shrinkage cracks by expansive additive, in: AIJ (Ed.) Summaries of technical papers of annual meeting, Nagoya, Japan, 2012, pp. 747-748.

- Volumetric mixture proportions were the same. Stress in mortar must be the same among specimens under the same drying and geometrical condition. Why visible cracks were differed under the same condition?


STRUCTURAL BEHAVIOR

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TARGET MEMBER

43

・Wall：T=180mm, Reinforcement:0.40%, D13 ・Columns: 850×600mm, Reinforcement:1.59% ・Beam: 850×450mm, Reinforcement:1.32%

Upper rebar：5-D25 Bottom rebar：5-D25

6900

850 5200 850

850

2200 3050

単位(mm)

450

850

850

600

Wall thickness is 18cm or 60cm

A. Sugie, I. Maruyama, M. Teshigawara, 21588 Numerical simulation for stiffness change of RC wall due to drying, Summaries of technical papers of annual meeting, 2014 (2014) 1175-1176.


MODEL - 2-D Isoparametric elements for concrete

•Smeared crack model •Tension: ¼- softening model. •Shear softening: Walraven’s model •Shrinkage is considered as equivalent nodal force.

- Line-element for reinforcement

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CRACK AND MODEL - Crack size is 1/4 of Mesh size (gauss point.) - Crack less than 1/4 Mesh should be considered in

constitutive low. Reduction of Young’s modulus is modeled as a function of water content. Creep coefficient is modeled as a function of water content.

45


CALCULATION PROCEDURE

46



CRACKS IN CASE OF LARGE SHRINKAGE CONCRETE

47



STIFFNESS

48

0 0.5 1 1.50

1000

2000

3000

4000

水平変位(mm)

荷重

(kN

)

0 0.5 1 1.50

1000

2000

3000

4000

水平変位(mm)

荷重

(kN

)

Initial　 28day91day 1year3year 10year理論式

LOAD

(kN

)

DEFORMATION (mm)

Initial

After 10 years



COMPARISON

49

12

kfmπ

=

剛性

質量固有振動数

0 2 4 6 8 100

0.2

0.4

0.6

0.8

1

各乾燥期間の固有振動数

/In

itial

(竣工時

)の固有振動数

(-)

year

C-G1C-G2C-G2 壁厚600mm女川原子力建屋建築研究所新館

Natural freq. Mass

Stiffness

Rat

io o

f nat

ural

freq

. (-)

Onagawa NPP

BRI bldg

Large shrinkage conc. (1100µ)

Small shrinkage conc. (800µ)

Thickness = 600 mm Large shrinkage conc. (1100µ)

- Order of reduction of natural frequency is reproduced. - Finishing coarting, detailed environmental conditions are not considered. A. Sugie, I. Maruyama, M. Teshigawara, 21588 Numerical simulation for stiffness change of RC wall due to drying, Summaries of technical papers of annual meeting, 2014 (2014) 1175-1176.


CONCLUSION : MULTI-SCALE MODELLING - Even we use a cascaded scale modeling, final mesh size

of numerical analysis should be comparable to the governing phenomenon of target physical property. It is important to understand the key scale which control the target phenomena.

- There are multi-scale cracking, we need multi-scale modeling of cracking. Minor cracks is considered implicitly as reduction of Young’s modulus in the present study.

- The modeling needs scientific background, not the experimental background for extraporating. We should collect scientific knowledge as possible as we can.

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WE NEED ACTUAL PERFORMANCE - Knowledge for design is not the same as that for aging

management, because we can not evaluate actual performance of concrete structure. Even it is beyond required performance, we need it.

- Numerical and experimental investigations for both actual performance and aging behavior are strongly needed.

- Multi-scale vision and insight for understanding the concrete structure should be enhanced by proposing working hypothesis through multi-scale modeling.

- Experiment from a view point of modelling and experiment to find something new are needed.

- Collaboration between numerical modeler and experimental investigator is the key for future research.

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Thank you for your kind attention

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