Yasuhiro Kojima
Research on Measuring Method of Airborne Salt and Estimation of Airborne Salt Around the Bridge Section by Numerical Simulation
Supervisor: Eiji Iwasaki
Recently, reduction of Life Cycle Cost (LCC) is important problem about the bridge, so that the weathering steel is a very attractive steel in the viewpoint of reduction of LCC because it can be used by uncoated. The following condition for unpainted weathering steel in Japan should be satisfied to generate a protective rust on the surface of the steel, namely maximum amount of marine salt is less than 0.05mdd (mg/dm2/day). In Japan, the dry gauze method or Doken tank method is used to measuring airborne salt. In these methods, measuring value depend on direction of gathering surface of these apparatuses. There is apprehensive that obtained value of airborne salt is difference between measured and actual. By the way, a state of corrosion is different in the part of the bridge. Accordingly, evaluation for amount of marine salt is needed at each part of the bridge.
In this study, influence of direction of gathering surface is investigated and new apparatus that doesn't depend on the direction of surface is proposed. Furthermore, marine salt around the bridge section is calculated by numerical simulation technique. The precision of marine salt around section of the bridge is discussed by comparison between numerical result and measurement of marine salt
Please use "previous botton" to return the previous page