How can you use vibration measurements to locate structural damage?

Vibration measurements involve studying how a structure responds to outside forces like wind, traffic, or earthquakes. Sensors like accelerometers or strain gauges are used to record acceleration, strain, or displacement at various points and frequencies. These measurements offer valuable insights into a structure's behavior, modal properties, and dynamic features.

Determination of natural frequencies, mode shapes and if you are lucky damping. Having determined these properties for 25+ bridges and a few dams and buildings. I can only say damage is local dynamic properties are global. Doing the testing is very valuable if you want to confirm the you analytical model represent the real structure. Given that typical structural analysis is based on ancient representations of damping you are guaranteed to get mode shapes which are just eigenvectors that are real (unfortunately structures don't go to UNI to learn how to behave. In reality you will measure complex mode shapes on physical structures that have partially filled reservoirs or challenging foundation conditions. It can only point out bad models!

You can use vibration measurements to locate structural damage by analyzing changes in vibration frequencies, amplitudes, and patterns over time. This helps pinpoint areas of structural weakness or damage, allowing for timely repairs and maintenance.

Vibration measurement is not cost effective and useful with traditional sensors for local damages especially on redundant structures and truss bridges.

It is very important that vibration measurements use to locate structural damage by analyzing changes in vibration, frequencies, amplitudes, and patterns over time. This helps pinpoint areas of structural weakness or damage, allowing for timely repairs and maintenance.

Dynamic vibration measurements are subject to thermal variation in in-determinant structures and loading. Thus tiny change in mass and stiffness matrices associated with localized damage are not able to picked up with global modes. If you can match the MAC of your model and the structure to better than 1% for the first 100modes you are a god! But if you read the literature of the last 40 years you can see that you can damage fracture critical bridges by cutting an entire bottom flange without seeing a change in mode shapes (see Sandia Lab publications). So while you can see the damage clearly you can't see it in the dynamic response! Vibration theory is based on elastic behaviour and it is not capable of predicting brittle failure

Frequency Response Function (FRF) Analysis: FRF analysis involves subjecting the structure to a known force input and measuring the resulting vibration response. By analyzing the FRF data, including resonance frequencies, damping ratios, and mode shapes, changes in the dynamic behavior due to structural damage can be detected.

Vibration measurements are valuable for damage detection because they offer a non-destructive and indirect way to assess a structure's health by analyzing its dynamic response.

Operational Deflection Shapes (ODS) Analysis: ODS analysis involves measuring the vibration response of the structure under operational conditions. It can help visualize how the structure deforms and vibrates during normal operation, allowing for the detection of localized damage-induced vibrations or changes in global structural behavior.

see my other answers on this topic having dealt with every thing from bad data to bad models and shitty instrumentation I wish everyone good luck with their grand applications and that I do not get to review them!

Damage Detection Algorithms: Various signal processing and statistical algorithms can be used to process vibration data for damage detection. These methods include changes in modal assurance criterion (MAC) values, curvature mode shape analysis, wavelet transforms, damage indices, and statistical pattern recognition techniques.

Think local act global is a common catch phrase. Good sensors properly filtered amplified and sampled are a good first stage. So now lets talk about the Blue water bridge near near Sarnia, Ontatrio, it typically has two lanes of fully loaded full loaded trailer trucks on it and there is a lane for cars in one direction. There are days when there is next to n truck loading (Covid) so the mass loading is and hence the measured dynamic properties are completely different. So do we a damage problem in either case? NO. But we have different vibration characteristics. You can't improve on this as the real world gives you more natural variability than you can detect in a lab. At certain Holidays

Distributed Sensing Technologies: Distributed sensing technologies, such as distributed optical fiber sensors or sensor networks, can provide detailed spatial information about structural response. This allows for the localization of damage by identifying changes in vibration characteristics across different parts of the structure.

Common sense and a good understanding of all the mathematical limits you have imposed on a far more complex building. If we only MRI people when we suspect something very wrong with them why would be "MRI" structures in the long term? Can you still sensor data from 40 or 60 years ago. If you have no data continuity then you have nothing.

Implementing vibration-based damage detection systems requires efficient data management, interdisciplinary collaboration, validation, calibration, and cost-effectiveness. Collaboration among experts ensures accurate interpretation of vibration measurements, while validation and calibration maintain reliability. Cost considerations prioritize cost-effective solutions for sensor installation, data management, and maintenance without compromising detection quality.

Remote Sensing and Structural Health Monitoring: Remote vibration sensing and structural health monitoring systems can continuously monitor the structural vibrations and detect deviations from expected behavior, enabling the early identification and localization of damage.