In recent years, many infrastructures have been deteriorating. In order to maintain sustainability of those infrastructures which have significant influence on social lifelines, economical and rational maintenance management should be carried out to evaluate the life cycle cost (LCC). The development of structural health monitoring systems, such as deriving evaluation techniques for the field structural condition of existing structures and identification techniques for the significant engineering properties of new structures, can be considered as the first step in resolving the above problem. New innovative evaluation methods need to be devised to identify the deterioration of infrastructures, e.g. steel tendons, cables in cable-stayed bridges and strands embedded in pre-or post-tensioned concrete structures. One of the possible solutions that show 'AtoE' characteristics, i.e., (a)ccuracy, (b)enefit, (c)ompendiousness, (d)urability and (e)ase of operation, elasto-magnetic (EM) actual stress sensory technology utilizing the sensitivity of incremental magnetic permeability to stress change, has been developed. Numerous verification tests on various steel materials have been conducted. By comparing with load cell, strain gage and other sensory technology measurement results, the actual stresses of steel tendons in a pre-stressed concrete structure at the following stages have been thoroughly investigated: (i) pre-stress change due to set-loss (anchorage slippage) at the tendon fixation stage; (ii) pre-stress change due to the tendon relaxation stage; (iii) concrete creep and shrinkage at the long term pre-stressing stage; (iv) pre-stress change in the cyclic fatigue loading stage; and (v) pre-stress change due to the re-pre-stress setting stage. As the result of this testing, it is confirmed that EM sensory technology enables one to measure actual stress in steel wire, strands and steel bars precisely without destroying the polyethylene covering sheath and enables one to provide adequate accuracy and reliability for monitoring actual stresses of those steel tendons during the life cycle of infrastructures. An example of a field application at a cable-stayed bridge is described.

We studied the relevance of the secular variation of Japanese interest in energy and environmental problems to the information primarily released by the news media. From the investigation of the extent of public interest in three matters, the global warming, the energy saving and nature, all indicated by opinion surveys, the number of newspaper articles and the frequency of Internet retrieval search, we proposed a model such that the public interest along with the acquired public knowledge were given as a function of public memory of the information primarily provided by the news media. The society was assumed here to be immersed in a virtual field of information environment, which induced the collective interest of the public and was proportional in strength to the extent of the public memory with oblivion. Introducing two types of oblivion function, we found the model to well reproduce the real time-variation of the Japanese interest, except for the case of nature, almost irrespective to the form of the function. Some comments were made on the attenuation of the public interest that occurred when the field became weakened.

Elasto-Magnetic ( E M) actual-stress measurement method by utilizing the sensitivity of incremental magnetic permeability due to stress change has been being developed. Previously, it has been proved that E M measurement method enable to measure actual-stress of steel wire, PC bar and PC strand contactlessly without destroying their polyethylene covering sheath. Furthermore monitoring tensile force of PC tendon is the most important issue in PC structure maintenance management. Therefore, in this paper, in order to grasp the reliability of E M sensor for field-application purpose, a test of tensile force monitoring on PC tendon of outer cable PC beam by utilizing E M sensor was conducted. As the result of the test, it is conformed that E M stress measurement technology can provide adequate accuracy and reliability to monitor tensile force of PC tendon during a life-cycle of PC structure.

Uniaxial compression experiments were carried out to study the strengths and failures of gypsum samples with some pre-existing flaws in non-overlapping geometry. These prepared samples were expected to have same strength by the stress analysis 14) which is based on the simplified linear mechanism. The experimental results demonstrate the effect of the sample's geometries on the compressive strengths, and the failure mechanisms governing the strength characteristics. And then the stress analyses were improved by using the extracted failure mechanisms. The improved analyses show that the predicted compressive strength agrees fairly well with that of experiments.

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