Abstract. Infrastructures in the world get old in several decades of their service time. Falling-offs of parts of deteriorated structures were often reported and sometimes caused casualties in Japan and many other countries. When an earthquake occurs, in particular, deteriorated structures have higher possibility to be damaged or collapsed. Thus assessing the health condition of structures is one of the important topics in civil engineering. Considering a large number of structures that have been in service more than 40 years in Japan, efficient evaluation methods are requested. In this regard, non-destructive tests have high possibility to be applied to various structures without affecting their functions. Accordingly, this study focuses on the use of infrared thermography to detect internal deterioration of concrete structures. As a first step of investigation, thermography diagnosis, hammer sounding test and Schmidt rebound hammer test were carried out to detect internal deterioration of a concrete retaining wall located in the campus of Chiba University, Chiba, Japan, and the results were compared to evaluate the capability and accuracy of these diagnosis methods.

Large tanks for storing petroleum are placed in various locations in Japan. The natural periods of liquid sloshing of these tanks are calculated from their diameters and contained liquid heights. The natural periods are approximately between 5 to 10 seconds and hence, petroleum tanks are affected by long-period seismic ground motion. Thus the sloshing phenomenon, oscillation of the contained liquid, may occur and sometimes fire will be associated. Considering this background, this study focuses on the sloshing phenomenon and the sloshing heights in the 2011 Tohoku-Oki earthquake were calculated to assess the fire risk in the Keiyo petrochemical industrial complex. The long-period ground motion due to the scenario Nankai-Trough earthquake was also employed for sloshing analysis at this site. From the calculation of sloshing heights and overflow amount of oil under various conditions, the method to prevent oil overflow was suggested for future earthquakes.