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Proceedings of the International Conference on
Advances and New Challenges in Earthquake
Engineering Research, Hong Kong Volume
r
STRUCTURAL HEALTH MONITORING FOR LARGE
STRUCTURES USING AMBIENT VIBRATIONS
Juan M Caicedo 1 , Enk Clayton 1 *, Shirley J Dyke 1 and Masato Abe 2
Department of Civil Engineering, Washington University in St. Louis
St. Louis, Missouri, USA
2 Department of Civil Engineering, University of Tokyo,
Tokyo, JAPAN
ABSTRACT
With the advent of more sophisticated computing software and hardware, the practicality
of effectively implementing ambient vibration based global structural health monitoring
algorithms has been greatly enhanced. These improvements have facilitated the implementation
of systems to measure the dynamic behavior of large structures such as sky
scrapers and long span bridges. These flexible structures have features that introduce additional
challenges to the field of structural health monitoring. This paper examines the effectiveness
of the Natural Excitation Technique (NExT) combined with the Eigensystem
Realization Algorithm (ERA) to identify modal parameters in such structures. Simulated
data from a mathematical model of the Bill Emerson Memorial Bridge is used. Ambient
vibrations, modeled as stationary broadband inputs, are used for exciting the model.
INTRODUCTION
Virtually every facet of our daily activities depends on the reliability of our civil infrastructure.
Long span bridges and tall buildings are costly to construct and can be critical to
the smooth operation of our nations' infrastructure. The loss or unnecessary closure of key
structures in the transportation network has severe consequences on regional or national
economies. There is a clear need to continuously maintain the function of these structures
well into the future.
Presently, simple yet time consuming and labor intensive methods such as visual inspection
and hammer echo are utilized in the field to monitor the health of structures such as
highway overpasses and tunnel linings. There are limitations concerning the implementation
of the these approaches, the most prominent being: the safety of those inspecting the
structures; the difficulty of inspecting large or inaccessible parts of structures; and, the inefficiency
of such time consuming approaches. As a result of the shortcomings found in
these methods, mathematically based global structural health monitoring (SHM) tech-
* Currently an undergraduate civil engineering student, Univ. of Tennessee, KnoxviIIe, Tennessee USA.