louis demilecamps comportement et evaluation des ouvrages speciaux « behaviour and assessment of...

Louis Demilecamps

COMPORTEMENT ET EVALUATION DES OUVRAGES SPECIAUX« Behaviour and Assessment of Special R.C. Works

Cracking & Shrinkage » www.ceosfr.org

RELIABLE SHRINKAGE AND CRACK DESIGN:Ceos French National Research Program

Experimental Aspects

http://www.ceosfr.org/

Reliable Shrinkage and Crack Design: CEOS Experimental Aspects

• CEOS.fr, a French National Research Program (2008-2011 : – Budget 8M€, 40 members:

• Companies: EDF, Vinci, Eiffage, Bouygues, Areva, Solétanche-Bachy, Italcementi, Iosis, Setec, Co&B, Arcadis,

Oxand, Necs, Advitam, Sites, Chryso, Rincent, Saipem, PX-Dam… • Lab. & Institutions: LCPC, CSTB, CEA, IRSN, ANDRA, ATHIL, CERIB, CEBTP, LERM, CETU…• Universities: ENS Cachan (LMT), INP Grenoble (3S-R), INSA Toulouse (LMDC), EC Nantes (GEM), U. Pau

(Lasagec), Polytech’ Lille (LML)…

• Aims: – at dealing with the control of cracking (a major concern for durability and sustainability), in particular for

special works (specific use, specific shape and size, specific requirements for loading or durability...)

• Subjects: – Cracking under monotonic loadings – Behavior under coupling loadings (THM) – Cracking under cyclic and seismic loadings

• Approaches: – Experiments on large specimens– Numerical modeling – Elaborated by engineers-practitioners

• International connection:– International benchmark (registration until Jun.15/10)

– European network under construction

May 29, 2010 23rd fib International Congress - 2010

Objectives of the experiment

• Trials are intended to provide basic data for the conventional calculation and the scientific models:

– additional data in order to finely tune numeric simulators

– additional data on scale effects and their incidence on the validity of the digital models

– data fitting the 3 targeted fields : static, cyclic, thermo-hydro-mechanical

The experiment does not aim at bringing out or characterizing some new phenomena or behaviors

CEOS.FR Experimental Part


Project Contents

Trials on Test Bodies

Program:

It will be performed through three

different series :- walls (shearing tests)- blocks (bending tests)- I-shaped blocks (shrinkage

test)

May 29, 2010 3rd fib International Congress - 2010 4

DESIGN TB

FABRICATE TB

TEST TB

MODELIZE TB

GOOD ACCORDANCE

PERFORM VIRTUAL TESTING

IMPLEMENT NEW CRITERIA IN ENGINEERING CODES

IMPROVE MODEL

NO

YES

COMPARE TEST AND MODEL RESULTS

Series 1: Cyclic Loading Tests on Walls, 1/3 Scale

• Shearing of thick reinforced concrete walls under cyclic solicitation up to cracking

• Evaluation of the cracking stage during and after seism

• Result data = crack opening + crack spacing

• The experiment results must:– Be usable as a reference data base for the improvements expected in

modelling– Be added to the other available data in order to allow in fine establishing

and/or verifying the cracking formulas


Cyclic Loading Tests on the WallsConstraints of Experimentation

• The test bodies must be representative of highly reinforced thick walls

• The behaviour must be tested beyond the ULS scale reduction

• The behaviour of reduced scaled test bodies must be similar to the one it would be on a full-sized scale concrete and reduced reinforcement bars with similar behaviour

• The reinforcement ratio must be considerably superior to the non-fragility limit

• The stress state and the cracking mode due to the cyclic solicitation must be perfectly identified


• Reinforcement ratio: from 0.5% to 1%, displayed in two layers

• Maximum jacking capacity = 4 MN limited resistance of reinforcement– Test body: 0.15m thick 1.05m high 4.2m long (H/L ratio = ¼)– Representing an “actual” wall: 0.45m 3.15m 12.6m

Cyclic Loading Tests on the Walls - Proposed Choices


Test N° Loading method Test body

1 Cyclic and alternate up to the ruin Concrete C25 - Dmax = 8 mm

One wire mesh per face HA10 sq. mesh 100x100mm

2 Monotonous and increasing up to the

ruin

Concrete C40 - Dmax = 8 mm One wire mesh per face

HA10 sq. mesh 100x100mm

3

4 Cyclic and alternate up to the ruin

Concrete C40 - Dmax = 8 mm One wire mesh per face HA8 sq. mesh 80x80mm

• Measurement of the flexion areas by image correlation• Extensometer (vibrating cords, Bragg nets optical fibres)• Determination of the thermo-hydric parameters of concrete• Verification of the overall displacements and deformations

Cyclic Tests – Instrumentation and Loading Process


Chargement quasi-statique alterné

-30

-20

-10

0

10

20

30

Nombre de cycles

Dép

lace

men

t im

po

sé

(mm

)

A B C D E F G H I J

Quasi-static alternate loading

Con

trol

led

disp

lace

men

t

Quantity of cycles

Series 2 & 3: ”Scale 1” Block Tests

• General arrangement:– Making of the purpose design

test bench– Making of 7 parallelepiped test

bodies - 6.1mx1.60mx0.80m(7.8m³) for free shrinkage tests

– Making of 3 I-shaped test bodies 7.7mx0.50mx0.80m(5.5m³) for restrained shrinkage tests

• Concreting and aging (28 days) of the blocks

• Setting up and tightening to the test slab

• 4 points bending up to cracking (upwards jacking in two rows)


Free shrinkage (large block: 6,10x1,6x0,8)• RL1: reference block : reference concrete, reference reinforcement

(percentage and diameter),• RL2: reference concrete, reduced reinforcement percentage, same

diameter,• RL3: reference concrete, same reinforcement percentage, reduced

diameter,• RL4: reference concrete, changed reinforcement arrangement (different

coating: 3 and 7cm),• RL5: reference reinforcement, changed concrete (/tensile strength),• RL6: study of the variation of one block to the other => reference block

must be made once again• RL7: reference block with local and controlled defects (PVC pipes for

instance)

Restrained shrinkage (reduced size tension member ~6.10x0.80x0.50)• THM8: same parameters as for RL1• THM9: reference concrete, minimum reinforcement• THM10: reference concrete, maximum reinforcement

“Scale 1” Block Tests - Experimental Program


Series 3: Block Tests - Restrained Shrinkage Block


Series 2: Block Tests - Free Shrinkage Blocks


RL Blocks:Shape / Reinforcement

• 1st RL block cast in October 2009

Block Tests (RL1 block)


• 9 temperature sensors• 3 hygrometry sensors

“Scale 1” Block Tests - Instrumentation of the Blocks


• 16+2 vibrating cord sensors

• 9 optical cord extensometers

(3 internal, 6 external)

• 12 reinforcement strain gauges



Measurement of forces and overall deformations



4 jacks + pressure sensors

15 displacement sensors

Deformation Measurement by Image Correlation

• Instrumentation based on the techniques of image correlation. Quantities to be observed:

– The crack layout during test

– The displacement field

– The limit conditions

– The crack openings

• Size of the test body => 4 cameras for 1 face, with partial image superposition

• Camera: Canon EOS 450D type, 4272x2848 pixels, 12 bit depth(1 pixel = 5m x 3 x 4272 = 0.39mm)

• Result accuracy: approx. 1/10th pixel (pessimistic estimation)=> measurement down to 39µ

Testing bench

Test body(different according to tests)

Picture 4Picture 3 Picture 2Picture 1

4 points bending test

Principle scheme of picture superposition


• Specific paint pattern applied on concrete surface



SN4060 SN4059 SN4057 SN4051 SN4053 SN4067 SN4068 SN4069 SN4145

12/14, 12h 12/14, 14h 12/14, 16h 12/14, 18h 12/14, 20h 12/14, 22h 12/15, 0h2009

-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00mm

15ème palier - Allongement maximum

Resserrage

Correlation between cracking pattern (ULS stage) and reinforcement arrangement



• Approximate position of the sensors

Detection and Localization of Crack by Acoustic Analysis


• Classification and localization for the sensors for acoustic events

Acoustic Analysis Data and Reports


• Calorimetric test on cement with Langavant bottle• QAB test on concrete• Young’s modulus and Poisson’s coefficient, compression strength at

short terms (6 terms at least for a maturometric follow up)• Tensile strength (same terms)• Cracking energy • Endogenous shrinkage• Drying shrinkage• Measurement of the weight loss for one 16*32 test body under

laboratory conditions (50% relative humidity)• Creeping tests at early age under tension and compression conditions• Ring tests under endogenous conditions• Thermal dilatation coefficient• Calorific capacity of concrete or aggregates and paste

All Series: Characterization of Concrete (Scheduled Program)


• CEOS.fr:– End of experiment: December 2010– End of project: June 2012– More information on (mainly in French!)

http://www.ceosfr.org

• International benchmark CONCRACK:– Open to research or engineering groups– Blind stage (June 15 to December 15, 2010)– Feed-back stage (January to April 2011)– Restitution workshop in Paris (May or June 2011)

http://www.concrack.org

Conclusion




louis demilecamps comportement et evaluation des ouvrages speciaux « behaviour and assessment of...

Documents

cracking evaluation

works cracking shrinkage

fib international congress

cracking formulas

cracking stage

cracking mode

cyclic loading tests

basic data