Makoto Kitagawa

Full-scale measurement of Akashi–Kaikyo Bridge during typhoon

Abstract Full-scale measurement data observed on the Akashi–Kaikyo Bridge during strong typhoons were analyzed. Power spectral density and spatial correlation of longitudinal velocity fluctuations were analyzed. PSD was well represented by Hino’s formula by changing the scaling parameter. Spatial correlation at two points was well represented not by the exponential formula but by an alternative coherence function based on isotropic turbulence theory. Decay factor in the exponential formula showed a weakly increasing trend with the increase in distance and wind speed. Bridge response of deck lateral deflection was also analyzed. Static deflection at winds with normal to the bridge axis was in good agreement with the analytical value. Gust factors of deck lateral deflection were mostly less than design specification.

CORROSION MECHANISM AND PROTECTION METHODS FOR SUSPENSION BRIDGE CABLES

The main cables of several Japanese suspension bridges were found to be corroded. To determine the corrosion mechanism, the environments inside the cables were investigated, and corrosion simulation tests of galvanised wires were carried out. These studies showed that the corrosion environment depends on the position within the cable, with the side parts being most susceptible to corrosion. A new anti-corrosion system was developed using S-shaped wrapping wires and improved pastes to overcome this problem. Cables protected by this system were compared in long-term exposure tests with cables protected by conventional systems, and showed improved anti-corrosion performance. Another new method, namely to pass dry air through the cables, is proposed. Preliminary tests showed this system to be promising in terms of improving the anti-corrosion properties of the cables.