1. Inverse Estimation of Concrete Properties Andrew Salisbury Civil Engineering November 27, 2006

2. Andrew Salisbury2 Key Points From the Last Talk  Background on concrete and its important thermal properties  Introduction to non-destructive evaluation and its uses in engineering  The ultimate goal of this research is to determine concrete strength from material properties using heat flow

3. November 27, 2006Andrew Salisbury3 This talk explains the process of determining concrete properties Temperature Variation and Measurement Modeling Parameter Estimation

4. November 27, 2006Andrew Salisbury4 Heat flow must be stimulated by an external source Solar radiation causes periodic heat input

5. November 27, 2006Andrew Salisbury5 Infrared thermography allows non-invasive measurement of surface temperatures Infrared image of a structure’s exterior reveals temperature variations. Bright red colors signal higher temperatures.

6. November 27, 2006Andrew Salisbury6 Modeling with the finite element method allows for temperature simulation Temperature and heat flux is calculated for each element Accuracy depends on the mesh size

7. November 27, 2006Andrew Salisbury7 Appropriate boundary conditions are essential for an accurate model 01234567 x 10 5 30 35 40 45 50 55 60 65 Time (Seconds) Temperature (C) The blue curve represents model temperatures while the red represents recorded ones

8. November 27, 2006Andrew Salisbury8 Parameter estimation requires an iterative optimization process Recorded Temperatures Generate Model Temperatures Calculate Error Otherwise, Change Model Parameters Make Initial Guess for Parameters Stop if Error Meets Tolerance

9. November 27, 2006Andrew Salisbury9 Results suggest that this process is accurate  3 parameters solved simultaneously with errors less than 10 percent  Degrees of freedom limit the number of independent unknowns  Not a major problem since density has the least variation and a constant value is often assumed

10. November 27, 2006Andrew Salisbury10 Summary and Future Outlook  Determining material properties is an iterative three step process  The process is non-invasive and can be used in many applications  Future research will study early age concrete and heat generation

11. November 27, 2006Andrew Salisbury11 Questions?

12. November 27, 2006Andrew Salisbury12 References Outdoor IR Thermography. (2006) [Online] Available http://www.imaging1.com/gallery/images/outdoor%20ir%20thermography%20e nergy%20audit%20scan.jpg. November 26, 2006. Global Optimization. (2006) [Online] Available http://mathworld.wolfram.com/images/eps-gif/GlobalOptimization_1000.gif November 26, 2006. Concrete Ready-Mix. (2006) [Online] Available http://www.concrete-readymix.com/3.jpg. November 26, 2006. Solarcrete Energy Efficient Buildings. (2006) [Online] Available http://www.solarcrete.com/precast-concrete-thermal-infrared-images.php. November 26, 2006.