Which sensor is not commonly used in structural health monitoring for bridges?

• A. Accelerometers
• B. Strain gauges
• C. Displacement sensors
• D. Humidity probes

Answer: (D)

In structural health monitoring for bridges, sensors are chosen to capture how the structure behaves and how it carries loads. Accelerometers track dynamic response and modal changes, strain gauges measure internal stresses, and displacement sensors monitor deflection and settlement. Humidity probes, while useful for environmental or corrosion risk assessment, don’t provide direct information about the current structural state or damage progression. They don’t sense vibration, strain, or deformation, which are the primary indicators of health in a bridge. So humidity probes are not commonly used as a core SHM sensor for bridges. They may be used as supplementary environmental data, but they don’t serve the main purpose of detecting structural integrity.