Introduction to Vibration-based Damage Detection

Structural health monitoring

1. Muyideen Abdulkareem ( Ph.D ) Short note on Vibration-Based Monitoring by 18 th October, 2019 [email protected] [phone] STRUCTURAL ASSESSMENT AND REPAIR (1033)

2. Structural monitoring: test(s) carried out to ascertain Safety Performance Maintenance Introduction Why monitor?

3. Collapsed Nanfangao b ridge, Taiwan. Introduction 6 dead 12 injured 6 missing

4. Collapsed Sampoong Departmental Store, South Korea. Introduction 500 dead 900 injured

5. Introduction Collapsed I-35 Mississippi River Bridge, USA. 12 dead 130 injured

6. Introduction Visual inspection (traditional) Time Access Cost Assessment So what happens to large and complex structures?

7. Solution? Introduction

8. Vibration-based monitoring: application of responses of structures to carry out structural assessment. Responses - Acceleration - Velocity -Displacement (Fast Fourier Transform (FFT) analyzers and computer system) by applying changes in stiffness due to damage F = m (elementary physics) F = m + c + k (real situation) Where F, m, , and are force, mass, acceleration, velocity and displacement respectively. C and k are damping and stiffness respectively.   Introduction

9. Medical doctor vs. Monitoring engineer Introduction Medical doctor Monitoring engineer

10. - Forced-vibration (input & output measurements) method Equipment: - Sensors - Impact hammer - Data acquisition system - computer system Disadvantages: - O perations - cost - damage Structures: - Plate - Beams - Slabs Techniques

11. - Ambient vibration (output-only measurements) method Equipment: - Sensors - Data acquisition system - computer system Advantages: - No disruption of o perations - Cheaper - Not hindered by size Structures: - Bridges - Control towers - Buildings - Pipelines - Dams Techniques

12. Equipment Impact Hammer Excite structure Data Acquisition System Data processing Accelerometer Capture the vibration acceleration

13. Equipment Electrodynamic shakers

14. Equipment Lateral channel blower Noise generator System Calibrator (sensor )

15. Laboratory testing

16. Field testing

17. Real case study: Burj Khalifa

18. Thank you for your attention Any questions?