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David Lehký , Zbyněk Keršner , Drahomír Novák

Lehký, Keršner , Novák – Determination of concrete stat istics using fracture test and inv . anal ysis based on FraMePID-3PB. DETERMINATION OF STATISTICAL MATERIAL PARAMETERS OF CONCRETE USING FRACTURE TEST AND INVERSE ANALYSIS BASED ON FraMePID –3PB TOOL.

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David Lehký , Zbyněk Keršner , Drahomír Novák

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  1. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB DETERMINATION OF STATISTICAL MATERIAL PARAMETERS OF CONCRETE USING FRACTURE TEST AND INVERSE ANALYSIS BASED ON FraMePID–3PB TOOL David Lehký,Zbyněk Keršner, DrahomírNovák Brno University of Technology, Brno, Czech Republic 5thREC, Brno, Czech Republic, 2012

  2. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Introduction, motivation Motivation for material parameters determination (strengths, fracture-mechanical): - comparison of different mixtures and composites (optimal content, type of fibres, etc.) - numerical modeling of structures (deterministic and statistical level) 5thREC, Brno, Czech Republic, 2012

  3. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Introduction, motivation The knowledge of fracture/mechanical parameters is fundamental for virtual modeling of elements and structures made of concrete. Key parameter: fracture energy and its variability Other important parameters of concrete are: modulus of elasticity, tensile and compressive strength, effective crack elongation, effective fracture toughness, etc. 5thREC, Brno, Czech Republic, 2012

  4. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Numerical modeling – parameters Numerical model of structure appropriate material model (e.g. 3D Nonlinear Cementitious, Microplane model, etc.) – – many material parameters Information about parameters: • experimental data • recommended formulas • engineering estimation 5thREC, Brno, Czech Republic, 2012

  5. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Numerical modeling – parameters Primary calculation: Correction of parameters: • „trial–and–error“ method • sophisticated identification methods • – artificial neural network based inverse analysis 5thREC, Brno, Czech Republic, 2012

  6. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Fracture experiment • Testing configuration : • 3-point bending test of beam with central edge notch • Determination of parameters: • effective crack model + • work-of-fracture method • ANN based inverse analysis L-d diagram 5thREC, Brno, Czech Republic, 2012

  7. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Statistical parameters identification • Two approaches: • Load-deflection “one-by-one” identification approach Material parameters are identified individually for each specimen (individual l-d diagram is used as an input of ANN). Subsequently, statistical assessment of parameters of all specimens is carried out. • Direct statistical parameters identification Random response of a structure is available in form of histograms and statistical moments (set of random l-d diagrams is used as an input of ANN). Statistical parameters are direct output of inverse analysis (ANN). 5thREC, Brno, Czech Republic, 2012

  8. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB ANN based inverse analysis – deterministic parameters Structural response Material model parameters Stochastic calculation (LHS) – training set for calibration of synaptic weights and biases 5thREC, Brno, Czech Republic, 2012

  9. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB ANN based inv. anal. – statistical param. (direct approach) Structural response Material model parameters Stochastic calculation (LHS) – training set for calibration of synaptic weights and biases 5thREC, Brno, Czech Republic, 2012

  10. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB FraMePID-3PB tool • Developed for fullyautomatic and easy to use ANN based identificationusing 3PB experimental data (l-d diagrams) • Designed for concretes of various strength and ages (large training set with relatively high variability of material parameters) • Prepared for testing of specimens with various notch depth – study of fracture process zone development and corresponding changes of fracture energy • Implemented experimental data filtering 5thREC, Brno, Czech Republic, 2012

  11. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB FraMePID-3PB tool • Robust ANN implemented and trained – significant time reduction compared to general identification tasks • FEM computational model implemented (ATENA software) – 3D Nonlinear Cementitious 2 material model • Subject of identification: – modulus of elasticityEc – tensile strength ft – fracture energy Gf • Export of identified parameters to clipboard, text file, ATENA .ccm file • Direct transfer to ATENA for verification via ATENA interface (in preparation) 5thREC, Brno, Czech Republic, 2012

  12. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Experimental testing campaign • Testing of stochastic properties of various concrete types, mixtures and ages (in cooperation with BOKU, Vienna and other industrial partners). • Comparison of fracture–mechanical parameters obtained from several testing configurations: – 3-point bending test– wedge splitting test – compression test • Development of stochastic properties database (statistical moments, distribution functions, correlation coefficients). • Results of 4 sets of different concrete types tested in 3-point bending configuration will be shown here. 5thREC, Brno, Czech Republic, 2012

  13. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB 3-point bending tests • Set I (C30/37 H) • 9 specimens • age 91 days • Set II (C25/30 B3) • 9 specimens • age 87 days • Set III (C25/30 XC1 GK16) • 9 specimens • age 67 days • Set IV (C20/25 XC1 GK16) • 8 specimens • age 66 days 5thREC, Brno, Czech Republic, 2012

  14. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB 3-point bending tests – l-d diagrams 5thREC, Brno, Czech Republic, 2012

  15. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Statistical parameters of set I (C30/37 H) 5thREC, Brno, Czech Republic, 2012

  16. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Statistical parameters of set II (C25/30 B3) 5thREC, Brno, Czech Republic, 2012

  17. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Statistical parameters of set III (C25/30 XC1 GK16) 5thREC, Brno, Czech Republic, 2012

  18. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Statistical parameters of set IV (C20/25 XC1 GK16) 5thREC, Brno, Czech Republic, 2012

  19. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Comparison of parameters among all 4 sets Effective crack model + work-of-fracture method Compressive strength fc Fracture energy Gf Modulus of elasticity Ec 5thREC, Brno, Czech Republic, 2012

  20. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Comparison of parameters among all 4 sets Effective crack model + work-of-fracture method Effective toughness Gce Volume density gc Effective fracture toughness KIce 5thREC, Brno, Czech Republic, 2012

  21. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Comparison of parameters among all 4 sets ANN based identification method Tensile strength ft Fracture energy Gf Modulus of elasticity Ec 5thREC, Brno, Czech Republic, 2012

  22. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Comparison of l-d diagrams: experiment vs. identification 5thREC, Brno, Czech Republic, 2012

  23. Lehký, Keršner, Novák – Determination of concrete statistics using fracture test and inv. analysis based on FraMePID-3PB Conclusions • Determination of fracture/mechanical parameters values: • Effective crack model + work-of-fracture method • ANN based identification method • FraMePID-3PB– tool for fully automatic and time-effective ANN based identification using 3PB experimental data • Recommended statistical parameters for stochastic nonlinear FEM analyses of beams/structures made of tested concretes 5thREC, Brno, Czech Republic, 2012

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