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Many natural disasters cause not only
critical situations for facilities and resident’s residents’ life, but also
significant damage to economy. It is obvious that quick rescue action must be
undertaken and that there are many problems due to the occurrence of secondary
disasters at rescue worksite. Basing Based on the previous study of deployable
structures and the concept of the multi-folding micro-structures, we propose a
new type of foldable bridge in form of scissor structure called the
Mobile-bridge?. In this paper, we discuss the vehicle passing test performed on
the real-scale Mobile-bridge in order to evaluate its mechanical
characteristics and application limits. Moreover, we verified the compatibility
between the result of calculations and experiments by means of theoretical
modelling. The results show that it is sufficient to treat the load as
equivalent nodal forces applied at the joints without including the stiffness
of the deck.
behavior is highly dependent upon the movement mechanisms present throughout
the structure. These mechanisms (e.g. bearing, joints, etc.) have a substantial
impact on the long-term durability and potential safety of the structure. A
major distinguisher between the varieties of movement systems is their
operating timescale. In some cases, they function rapidly, within fractions
of a second, and in other cases gradually over days, months or even years.
However, in nearly all cases, the lifecycle of the movement system is shorter
than that of the bridge assuring the need for future intervention. Breakdown of
a movement system can produce unintended forces/deformations that
progressively degrade the structure. Identification and tracking of movement
mechanisms proactively address long-term durability by helping to avoid these
unintended consequences. A general framework for characterization of these
mechanisms was developed. This framework was applied to an operating bridge
that includes several critical mechanisms operating over different
timescales. As a result of this and other studies, recommendations are provided
for identification of bridge movement systems.
Several complaints arose from houses near an object bridge about rattling sounds caused by infrasound, a low-frequency noise in the 0 - 20 Hz frequency range. In Japan, conventional trucks with a rear leaf suspension have vibration frequencies of about 3.0 Hz; furthermore, their tire spring vibration frequency is 10 - 20 Hz. Infrasound is radiated from the bridge owing to the truck’s suspension spring vibration and/or tire spring vibration. In this study, the bridge vibrations were investigated using test trucks or conventional trucks to determine the cause of rattling sounds. It was found that the truck’s spring vibration caused excessive bending vibration in the object bridge; this in turn was transmitted to nearby houses as infrasound. Various preventive measures for infrasound were then considered, and their effectiveness was investigated through a simulation of the dynamic response using a running truck. The difference between each measure’s effectiveness as obtained by a comparison with each simulation’s result provided a clear picture about the infrasound reduction methods in consideration of both construction cost and working difficulty.