ECONOMICAL DEHUMIDIFICATION DESIGN AND ACTUAL PROOF EXAMINATION OF BOX GIRDER BRIDGE

Abstract

A method of dehumidifying the inside of box girders by reducing the moisture of the inner humid air is proposed at Hakucho Bridge. The inside of the girders is highly sealed space, so it could keep dry condition if the moisture taken from the outside is dehumidified. Numerical results indicate that the dehumidifier with 120m³/h capacity can easily dry 3,000m³ space below 40%RH (Relative Humidity). In a large suspension bridge, part of the box girder is sealed (3,200m³), and the dehumidification equipment is installed. It was confirmed that high humid (more than 60%RH) was reduced to 40%RH or even less. A model, which can simulate the humidity change measured in the bridge, is developed and a design procedure is presented.