The bolt joints on steel structures are exposed to the possibility of damage, and thus, require intensive care. Usually,
periodic inspections are conducted at the cost of time and money. However, it is very difficult to check so many bolts
carefully. The purpose of this study is to propose a system that can more efficiently monitor the tightness/looseness of
these bolts. The proposed bolt fastening monitoring system is comprised of sensors that are attached to nuts and a data
receiving terminal, which gathers information. The reed switch consists of two thin, metallic contacts enveloped in a
glass tube and is an electrical switching sensor that is triggered ON or OFF by changes in the surrounding magnetic field.
The verification tests showed that bolt loosening can be effectively detected, proving the applicability of this system to
the maintenance of the bolt joints of steel structures. The newly developed sensor system is expected to solve
conventional sensor problems by enabling measurement of structural members which was not previously possible, thus
providing a basis for a new technology in the construction industry by applying IT to construction technology.
Generally, the management criteria by monitoring items applied to the bridge management is decided through the
intuition of the based on the empirical data without any professional and systematic background. In this study, the span
deflection is selected among the bridge monitoring items and verify the appropriate management criteria in the case of
deflection by the laboratory test. Test specimens are the small-sizing bridge specimens which are made by reinforced
concrete. Those are classified by variation of span length and stiffness of section. As a result of test, the relationship
between the span center deflection and the safety level of bridge is suggested.
The rapid growth in the smart sensor technology (SST) has enabled easier and more economic construction of the
structural health monitoring system (SHM). Nevertheless, there is no distributed damage detection algorithm for efficient
usage of the computation power of the SST. Therefore, this study aims at developing a new distributed damage detection
algorithm suitable for the smart sensor system for the SHM. The algorithm suggested in this study utilizes the damping
ratio of a structure, using the structure's energy dissipation ratio. In other words, each smart sensor installed to the
structure analyzes the response signals from the structure into a damping ratio, which in turn is computed into an energy
dissipation ratio, using the smart sensor's ability to handle data. Thus, this method detects the damages and locations of
the damages in a structure using the changes in the energy dissipation ratio it has calculated. In this study proves the
usefulness of the developed energy dissipation ratio by numerical simulation.