Department of Civil Engineering, Nagoya Institute of Technology
Structural/Earthquake Engineering Laboratory
Investigation of Corrosive Environment of Bridge
and its Numerical Simulation

In-situ monitoring of corrosive environment of a bridge
ACM corrosion sensors and temperature humidity sensor are set up at a bridge.

ACM sensor (upper left) and Actual investigation situation


Mechanism of ACM sensor

Results (Point: measured value, Line: calibrated curve)
ACM(Atmospheric Corrosion Monitor)
Water adsorption on the surface of sensor by the condensation
Corrosion current is generated by oxidation and reduction reaction on the surface of the sensor.
Measure the corrosion current and monitor corrosive environment
Estimation of Amount of Adhesive Salinity and Steel Corroding Speed
  • Estimate the amount of adhesive salinity based on the calibrated curve
  • Calculate the steel corroding speed from the measured results
Predict the corrosion prone location

Application of CFD to Corrosive Environment Simulation in Bridge Neighborhood
The condensation of water plays a critical role in corrosion process of a steel bridge
Numerical simulation by Computational Fluid Dynamics (CFD)

Expression of Condensation and Evaporation of a Water
  • The condensation is represented by the growth of the water drop of a minute hemisphere adhering to a wall surface
  • Compute the heat flow among air, a drop and a wall to get a consistent result
Simulation of Evaporation Inside a box-girder
Simulation of the evaporation in a box girder when a ceiling of the girder is cooled down.

Evaporation speed is six times slower in the ceiling than that on the side and the floor.
  • Difference of temperature of wall
  • Rise of relative humidity near ceiling
The corrosive environment in the ceiling becomes severe compared with other sides when water condensation occurs

Distribution of water drops

Distribution of humidity

Acquisition of large scale environmental Information by meso-scale Atmospheric Model
Local meteorological data is necessary for proper boundary and initial conditions for local CFD analysis
The large scale environmental data is obtained by meso-scale atmospheric model(e.g., MM5, WRF).

Flow chart of MM5 model

Comparison of the distribution of atmospheric pressure

Comparison to Nagoya meteorological observatory (Temperature, relative humidity, wind velocity)