Structural health monitoring (SHM) is the process of using damage detection and characterization techniques for critical structures like bridges, wind turbines, and tunnels. It is a non-destructive in-situ structural evaluation method that employs several types of sensors embedded or attached to the structure.
The structural health monitoring process includes installing sensors, data acquisition, data transfer, and diagnostics through which the structure's safety, strength, integrity, and performance are monitored. If overloading or any other defects are observed, proper correction measures are suggested.
The Purpose of Structural Health Monitoring
- Improve performance (safety and functionality) of existing structures.
- The placement of sensors during construction works enables observers to assess the structure's condition and specify its remaining life span.
- Evaluate the integrity of a structure after earthquakes.
- Structural monitoring and assessment are essential for on-time and cost-effective maintenance. So, it reduces construction work and increases maintenance activities.
- The SHM process collects data on the realistic performance of structures. This data can help design better structures in the future.
- Shift towards a performance-based design philosophy.
Components of Structural Health Monitoring System
The structural health monitoring system consists of several components which are presented schematically in Figure-1 and discussed below:
1. Structure
The critical structures like bridges, tunnels, dams, and wind turbines are mostly monitored as they are a vital part of the national infrastructure.
2. Data Acquisition System
Data acquisition addresses the number and type of sensors, how to activate sensors, and techniques to save data. The placement of sensors should not alter the behavior of the structure. This can be achieved by considering the placement of wiring, boxing, etc., at the design stage.
Sensors need to be appropriate and robust and serve their function adequately for a specified duration. Each sensor may evaluate a particular aspect of the structure. They measure strain, deflection, rotation, temperature, corrosion, prestressing, etc.
Several types of sensors are available, such as those provided in Table-1, to be employed, but fiber optic sensors are the latest ones suitable for infrastructure.