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					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




                                     Louis Demilecamps
    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                            3rd fib International Congress - 2010                                        2
                   CEOS.FR Experimental Part

                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
 May 29, 2010           3rd fib International Congress - 2010       3
                         Project Contents
                                                                 DESIGN TB
Trials on Test Bodies
                                           FABRICATE TB                      MODELIZE TB


Program:
                                              TEST TB
                                                                                       IMPROVE MODEL


                                                          COMPARE TEST AND
                                                           MODEL RESULTS


It will be performed through three
                                                                GOOD
different series :                                           ACCORDANCE
                                                                                     NO


-              walls (shearing tests)
                                                                   YES
-              blocks (bending tests)
                                                          PERFORM VIRTUAL
-              I-shaped blocks (shrinkage                     TESTING


test)
                                          IMPLEMENT NEW CRITERIA IN ENGINEERING CODES


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


 May 29, 2010                 3rd fib International Congress - 2010                5
                    Cyclic Loading Tests on the Walls
                     Constraints 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

    May 29, 2010              3rd fib International Congress - 2010            6
  Cyclic Loading Tests on the Walls - Proposed Choices

• 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
      Test N°            Loading method                                  Test body
                                                               Concrete C25 - Dmax = 8 mm
          1      Cyclic and alternate up to the ruin             One wire mesh per face
                                                                HA10 sq. mesh 100x100mm
                                                               Concrete C40 - Dmax = 8 mm
                Monotonous and increasing up to the
          2                                                      One wire mesh per face
                              ruin
                                                                HA10 sq. mesh 100x100mm

          3                                                    Concrete C40 - Dmax = 8 mm
                 Cyclic and alternate up to the ruin             One wire mesh per face
          4                                                      HA8 sq. mesh 80x80mm


 May 29, 2010                    3rd fib International Congress - 2010                      7
       Cyclic Tests – Instrumentation and Loading Process

•    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

                                                          Chargement quasi-statique alterné
                                                           Quasi-static alternate loading
                                            30
           Controlled displacement
             Déplacement imposé




                                            20

                                            10
                                     (mm)




                                             0

                                            -10

                                            -20

                                            -30
                                                  A   B       C        D        E        F           G   H   I   J
                                                                       Nombre de cycles
                                                                    Quantity of cycles
    May 29, 2010                                             3rd fib International Congress - 2010                   8
                 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)

  May 29, 2010             3rd fib International Congress - 2010   9
             “Scale 1” Block Tests - Experimental Program

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

    May 29, 2010               3rd fib International Congress - 2010             10
    Series 3: Block Tests - Restrained Shrinkage Block




May 29, 2010        3rd fib International Congress - 2010   11
          Series 2: Block Tests - Free Shrinkage Blocks




RL Blocks:
Shape / Reinforcement




 May 29, 2010           3rd fib International Congress - 2010   12
                Block Tests (RL1 block)

• 1st RL block cast in October 2009




 May 29, 2010      3rd fib International Congress - 2010   13
   “Scale 1” Block Tests - Instrumentation of the Blocks




• 9 temperature sensors
• 3 hygrometry sensors


 May 29, 2010       3rd fib International Congress - 2010   14
   “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
 May 29, 2010          3rd fib International Congress - 2010   15
  “Scale 1” Block Tests - Instrumentation of the Blocks




               4 jacks + pressure sensors
               15 displacement sensors




         Measurement of forces and overall deformations

May 29, 2010                      3rd fib International Congress - 2010   16
       Deformation Measurement by Image Correlation

                                                                     •    Instrumentation based on the
                                                                          techniques of image correlation.
                                                                          Quantities to be observed:
                        Test body
              (different according to tests)
                                                                           – The crack layout during test
                                                                           – The displacement field
                    Testing bench                                          – The limit conditions
                                                                           – The crack openings
              4 points bending test
                                                                     •    Size of the test body => 4 cameras for 1
                                                                          face, with partial image superposition
                                                                     •    Camera: Canon EOS 450D type,
  Picture 1       Picture 2        Picture 3   Picture 4                  4272x2848 pixels, 12 bit depth
                                                                          (1 pixel = 5m x 3 x 4272 = 0.39mm)
   Principle scheme of picture superposition
                                                                     •    Result accuracy: approx. 1/10th pixel
                                                                          (pessimistic estimation)
                                                                          => measurement down to 39µ


May 29, 2010                                   3rd fib International Congress - 2010                           17
        Deformation Measurement by Image Correlation

• Specific paint pattern applied on concrete surface




 May 29, 2010         3rd fib International Congress - 2010   18
                 Deformation Measurement by Image Correlation
   SN4060        SN4059       SN4057   SN4051     SN4053       SN4067       SN4068       SN4069   SN4145
mm 4.00
   3.75
   3.50
   3.25                                         15ème palier - Allongement maximum
   3.00
   2.75
   2.50
   2.25
   2.00
   1.75
   1.50
   1.25
   1.00
   0.75
   0.50
   0.25     Resserrage
   0.00
  -0.25
  -0.50
  -0.75
  -1.00

                          12/14, 12h      12/14, 14h           12/14, 16h            12/14, 18h      12/14, 20h   12/14, 22h    12/15, 0h
          2009

     Correlation between cracking pattern (ULS stage) and reinforcement arrangement
          May 29, 2010                                 3rd fib International Congress - 2010                                   19
Detection and Localization of Crack by Acoustic Analysis

• Approximate position of the sensors




 May 29, 2010        3rd fib International Congress - 2010   20
                Acoustic Analysis Data and Reports

• Classification and localization for the sensors for acoustic
  events




 May 29, 2010           3rd fib International Congress - 2010    21
 All Series: Characterization of Concrete (Scheduled Program)

• 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

  May 29, 2010           3rd fib International Congress - 2010       22
                             Conclusion

• 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
 May 29, 2010          3rd fib International Congress - 2010   23

				
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