Yusuke OKUYAMA
Development of Repairing and Reinforcing Method for Corroded members in Steel girder by Carbon Fiber Reinforced Plastic
Masatsugu NAGAI
Most of the deterioration for steel bridges is the corrosion. During their service period, progress of corrosion is inevitable due to the influence from surrounding circumstance. The conventional methods repairing and reinforcing the damage are the replacement of corroded members or the attachment of steel plate on them. However, these methods are regulated under service time because of requiring heavy machineries. Therefore, efficient and rational method repairing and reinforcing the damage is strongly needed.
In this situation, Fiber Reinforced Plastics (FRP) has been paid to attentions due to light weight and high stiffness, and many studies have been reported so far. Previous studies mainly focus on the applications to members subjected to normal stress; flanges in a steel girder bridge or chord members in a steel truss bridge. However, corrosions in the steel bridges mostly occur at webs near the ends of supports where shear force with large deformation at the ultimate state is dominant. Here, although debonding of FRP under large deformation becomes a problem, this type of investigation has never been reported so far.
Therefore, the objective of this research is to carry out a fundamental study on rational repair and reinforcement of webs in corroded steel girder bridges using FRP. Uniaxial compression test of steel plates bonded by various FRP sheets is carried out and shear buckling test of steel girder bonded by FRP sheets is carried out. Uniaxial compression test aims to select FRP sheets that have reinforcing effect following large deformation induced by buckling. Furthermore, a layer of polyurea putty is inserted between the steel plate and the FRP sheet and its effect is investigated. Shear buckling test aims to study bonding method of FRP sheets.
As a result, the followings can be concluded from this study.
1) The polyurea putty inserted between the steel plate and the FRP sheet is quite effective to prevent debonding with following large deformation.
2) The effective combination of FRP sheets attached on the steel plate is that the low and high modulus FRP sheets are attached on the inner and outer layers respectively.
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