Structural health monitoring for civil structures by using normalized modal strain approach | |
| Author | Le, Thi Hang |
| Call Number | AIT Diss no.ST-23-02 |
| Subject(s) | Structural health monitoring Reinforced concrete construction |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ST-23-02 |
| Abstract | Structural health monitoring using ambient vibration measurement has drawn significant attention due to its ease of operation and lower cost than traditional measurement methods. Most techniques based on ambient vibration measurement employ measurement acceleration or velocity time history data to compute dynamic characteristics such as fundamental periods, damping ratios, and vibration mode shapes, which are non-stationary and insensitive to small or local damage. In this study, we explored a scheme that adopts dynamic strain signals for the construction of modal strain patterns in civil structures for structural health monitoring systems. Dynamic strain measurements were performed using piezoresistive strain gauges with a strain resolution of 0.02 µɛ. The study involved testing a simply supported beam structure subjected to a known load with non-uniform damage severity. Strain gauges were installed along the axis of the reinforcement bar to detect the severity of the damage and track the load curvature response of the structure, allowing for the study of concrete mechanics. The results showed good agreement between the neutral axis position and modal strain pattern obtained from random excitation strain measurement and finite element analysis. The location and the severity of the damage can be identified by normalized model strain and neutral axis even at an early stage, in contrast to the conventional technique, which is based on a natural frequency that is insensitive to early damage levels. After verifying the method's capability for damage detection and localization on a reinforced concrete beam, it was deployed on a real-scale balanced cantilever bridge in Thailand to assess the structure's condition. A digital model of the bridge was created using the elastic modulus of concrete evaluated by the ultrasonic pulse velocity (UPV) technique and detailed geometrical information from the LiDAR 3D scan. The modal strain pattern and neutral axis of the bridge were constructed as a baseline reference for future comparison to detect any possible damage. |
| Year | 2023 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ST-23-02 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Pennung Warnitchai;Punchet Thammarak (Co-Chairperson); |
| Examination Committee(s) | Anwar, Naveed;Chao, Kuo Chieh; |
| Scholarship Donor(s) | AITCV Silver Anniversary Scholarships;AIT Fellowship; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2023 |