The objective of this study is to develop a nondestructive damage evaluation
methodology that can identify simultaneously both stiffness and damping changes in a
structure. Two approaches are used to meet the stated objectives. First, a method is
developed on the basis of the conservation of total energy; second, the other method
utilizes the acceleration-structural parameters (stiffness and damping) sensitivities. The
total energy in a system consists of the sum of the kinetic energy, the potential energy,
and the dissipated energy. In the second approach, a baseline structure is first identified.
A baseline structure is defined to be a structural system having a similar dynamic
response to the existing structure with no damage. In this study, natural frequencies and
modal damping values are used to identify the baseline structure.
The performance of the developed methodology is validated using several
numerical experiments; Two classes of structures are considered here: (1) a high-rise
building modeled as shear beams and (2) a two-span continuous beam structure. In the
shear beam model of the structure, the damping damage is simulated by increasing the
Newtonian dash pot constant which models the dissipation at the damaged story. For the
two-span continuous beam structure, it is assumed that damping of the undamaged
structure can be modeled using a proportional damping matrix. The damping matrix of
the damaged structure is modeled as the combination of a proportional damping matrix of the undamaged structure and a stiffness proportional damping matrix of the damaged
element.
Three damage cases are investigated for each of the two structures considered
here. Only one element experiences damping damage for the first damage scenario. In
the second damage scenario, both stiffness damage and damping damage are simulated
with different severities in one element of the model. In the third damage scenario, two
elements are simulated with stiffness damage and damping damage, to verify whether or
not the developed methodology works for multi-damage cases.
The proposed method is modified to use mode shapes and the modified proposed
method is applied to experimental data to identify stiffness damage in a R/C structure.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2472 |
| Date | 15 May 2009 |
| Creators | Hyung, Sang Su |
| Contributors | Stubbs, Norris |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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