Identification of Structural Damage in Civil Engineering
Civil engineering systems such as bridges, buildings, and dams are critical to survival and well-being of our society. Because of my education and background, the emphasis of these lectures is placed on the damage identification of existing structures.
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J.T.P. Yao Purdue UniYenity, W. Lalayette, U.S.A.
INTROOUC'riON Civil engineering systems such as bridges, buildings, and critical to survival and well-being of our society. tion and background, the emphasis of these
dams
are
Because of my educa-
lectures
is
placed
on
the
simplify
and
damage identification of existing structures. To make mathematical analyses, idealize
the
structural
system
it and
is its
necessary
to
environment. The design of a
structure follows an iterative process involving both structural analysis and
structural
design
using generalized mathematical models, whieh are
based on experienee and available knowledge in sion.
Using
field
data
design is made and the
and
the
engineering
profes-
other relevant information, a preliminary
idealized
mathematieal
H. G. Natke (ed.), Application of System Identification in Engineering © Springer-Verlag Wien 1988
model
is
analyzed
for
J.T.P. Yao
350
expected or specified loading conditions.
Based on these analytiral stu-
dies, the design may be revised and re-analyzed in all
until
design
criteria
an
iterative
manner
are satisfied. The rompleted design is then
constructed accordingly. For structures which have been construrted and are thus existing, it times
at
necessary
is
to assess their respective darnage states on the
basis of available information including measured and recorded experimental
data.
In
addition, it is desirable to evaluate the reliability of
these structures so that rational decisions can be made concerning neressary repairs, replacements, retirement, and other maintenance or rehabilitation procedures as shown in Fig. 1.
Time
Foeld Work
•
Operation
l~~--~------~
__t_____:: --r-f---'--..,-----'----, t
lnspectoon and Test Data
Office Werk
Conception Planning
r----- ,
Expected I Math M0d11l I EnvoronCond I for Structure 1 Response
•L------
Satety Evaluation Dlt I,Riti,LI t I
D
Domage R Resodual Strength
L
Rellabollty
Fog 1 : RoJe of Structural ldenllfocatoon I From Yao. 1985 I
351
Structural Darnage in Civil Engineering
Because (a) it is difficult to predict future loading conditions and (b)
material
properties are random in nature, stochastic processes have
been used to represent these quantities for probabilities.
the
structure
is
an
phase
extremely complex system.
because
the
real-
difficult
to
all the details in the mathematical model of a given structure.
Moreover, the damage path and failure behavior of most remain
failure
Even with the use of
finite element methods and modern computers, it is usually consider
of
However, the as-built structure is usually different from
the original mathematical model in the design world
estimation
large
structures
unknown because few experimental studies of full-scale structures
have been conducted to-date. For important structures, nondestructive dynamic tests are conducted for
the
estimation
of
dynamic
properties
of the as-built structure.
These test data are then used to obtain "impro
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