The importance of SHM systems in public safety
cannot be stressed enough. A myriad of SHM systems are currently
being employed, worldwide, to monitor everything from the strength
of structural components in the worlds tallest skyscrapers,
longest bridges and tunnels, to micro-fractures in oil pipelines
and temperature related performance changes in tarmac materials.
The information provided by an SHM system in invaluable for safety
in that it allows for the early detection of structural damage
and an informed, rapid repair response. Thus, SHM systems can
be invaluable in their ability to prevent life threatening and
catastrophic disasters by prevention, early detection and repair.
Inspection and preventative maintenance:
In conjunction with periodic visual inspection, or when visual inspection
is not possible, SHMs ability to detect microscopic areas
of damage can greatly enhances any existing maintenance program.
Real-time management and control:
By continuously monitoring and reporting structural responses in
a time synchronized manner, SHMs give engineers the ability
to have the most up-to-date knowledge of the condition of a structure.
Subsequently, the system can be managed, in real-time (for example,
adjusting sensor node sampling rates and parameter ranges).
Post catastrophic event assessment:
During emergency management situations, SHMs can provide rapid,
post-event assessment data. This allows for a knowledge-based response
that can minimize potential casualties and property damage
Bridge Monitoring: Safety and health
of bridges is one of the most common applications for SHM. SHM
networks can be skillfully applied to all bridge types in order
to extract the most useful information. Common bridge types include:
beam, truss, cantilever, arch, suspension, fixed, movable and
Building Monitoring: Buildings with extreme
architectural design, such as skyscrapers, are particularly vulnerable
to damage from common daily, and catastrophic, forces. SHM monitoring
and, model testing systems, allow civil engineers to gain insight
into a buildings structural response to a wide variety of stresses.
In this way, designs can be modified and refined as needed. Common
skyscraper construction models include, steel frame and tubular;
with trussed cross bracing, bundled and concrete.
Tunnel Monitoring: SHM systems can provide
early failure warning for all tunnel types, allowing minor preventative
repairs before catastrophic failures occur. There are three basic
types of tunnel construction in common use: Cut and cover tunnels
(constructed in a shallow trench and then covered over), bored
tunnels (constructed in situ, without removing the ground above)
and immersed tube tunnels (sunk into a body of water).
Dam Monitoring: In addition to the dam
structure itself, SHM can monitor: permeability of the surrounding
rock or soil for the determination of earthquake, landslide and
slope stability; as well as water table and peak flood flows.
The major dam types include arch gravity, barrage, embankment
(rock, concrete, earth fill) and cofferdam.
Wind Turbine Monitoring: SHM allows for
remote management of individual wind turbines as well as the collective
management of the entire wind turbine farm.
Earthquake Monitoring: SHM allows real-time
monitoring of structures located in seismic zones. Data can be
used to improve the understanding of, and create predictive modeling
for, a structures response to an earthquake. SHM data may also
help to aid in post-earthquake response and recovery.
Composite Materials: Composite materials
are widely applied in many engineering applications, due to their
unique physical properties such as: high strength-to-weight ratio,
increased resistance to fatigue and low thermal expansion. Although
invaluable for construction, it is often difficult to detect damage
within a composite material due to the complexity of its response
to loads and forces.
Therefore, creating novel SHM approaches for monitoring composites
is crucial for building safe composite structures. Examples of
composite materials include, fiberglass embedded high performance
concrete and ceramic embedded soft metals. In addition, smart
materials have been created that actually build the SHM
sensors directly into the composite material.