KASUN DHARMASIRI
Department of Civil Engineering
(Fourth Year)
Rail’s safe structure system on a bridge • Source: http://alliancesensors.com
situations where post structural integrity
damping ratios etc. The vibration charac-
is of concern.
teristics could be extracted from the time
history data collected from acceleration
As explained earlier, the damage detec-
transducers employed in specific locations
tion methods in use mostly depend on
of the structure excited either by artificial
visual inspection. However, it is difficult
means or free vibration, after analysis. In
to detect damages in the structure using
order to assess damage, a comparison has
visual inspection until the damages in the
to be made between two structural health
structure have turned out to be promi-
states. However, researches are being car-
nent; say spalling of concrete in the soffit
ried out to use the non-linear behavior
surface, cracking and other deformations.
to identify damages rendering the need
to compare two structural health states
Furthermore, use of visual inspection has
redundant.
certain limitations such as accessibility
issues and visibility issues, which may
It is evident that use of VBDD to detect
deem the method useless in certain cases.
damages is a possibility and if not com-
To address these issues, various dam-
pletely replace, adopt it as a complemen-
age detection techniques have emerged
tary method to detect damages along with
during the past years such as acoustic
visual inspection.
or ultrasonic, magnetic field, x-ray, radiographic, eddy current and vibration based
damage detection techniques.
References
1. Brownjohn, J.M.W., 2007. ‘Structural
Vibration Based Damage Detection (VBDD)
health monitoring of civil infrastructure’.
has a greater potential mainly because it
Philosophical Transactions of the Royal
is a non-destructive method, addresses
Society A: Mathematical, Physical and
issues related to accessibility and visibil-
Engineering Sciences 365, 589–622.
ity of damages and can be programmed
2. Chang, P.C., Flatau, A., Liu, S.C., 2003.
to run autonomously. The basis of VBDD
‘Review Paper: Health Monitoring of
is that dynamic response of a structure
Civil Infrastructure’. Structural Health
changes with damages it has accumulated
Monitoring 2, 257–267.
over its service life. This is based on the
3. Wang, L., Chan, T.H., 2009. ‘Review of
hypothesis that due to damages, the stiff-
vibration-based damage detection and
ness of the structure alters (drops) leading
condition assessment of bridge struc-
to changes in vibration characteristics
tures using structural health monitoring’.
such as modal frequencies, mode shapes,
In:QUT Conference Proceedings.
Source: http://en.wikipedia.org
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