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Proceedings of the International Conference on
Advances and New Challenges in Earthquake
Engineering Research, Hong Kong Volume
INNOVATIVE APPROACHES FOR STRUCTURAL HEALTH
MONITORING OF INTELLIGENT INFRASTRUCTURE SYSTEMS
Raymond W. Wolfe 1 , Sami F. Masri 2 , and John Caffrey 2
Supervising Bridge Engineer, California Department of Transportation, Sacramento, CA, USA
2 Department of Civil Engineering, University of Southern California, Los Angeles, CA, USA
ABSTRACT
Intelligent infrastructure components (e.g., MR dampers) possessing adaptive features
are being seriously considered for deployment in civil infrastructure systems in highly
seismic regions throughout the world. Due to the long service life and harsh
environments that such components may be subjected to, it is essential to have a
reliable and efficient procedure for condition assessment of these components based
on the analysis of their vibration signature.
This paper presents an overview of some promising approaches based on nonlinear
system identification techniques to detect slight changes in the characteristics of
nonlinear dampers of the type commonly encountered in structural control
applications involving large civil infrastructure systems such as bridges. By
characterizing the restoring-force surface of the damper in a nonparametric form, and
subsequently analyzing the higher-order statistics of the coefficients defining such
surfaces, it is found that the associated probability density function of the identified
coefficients furnishes a sensitive indicator of the underlying damper parameters. Both
simulation results as well as experimental measurements from a prototype nonlinear
viscous damper are presented to illustrate the approach and discuss its range of
validity. Sensor requirements for field implementation are also discussed.
1. INTRODUCTION
Large-scale civil infrastructure design and construction present an interesting class of
problems related to the large dynamic demands from wind and seismic events.
Engineers are searching for new ways to handle the large forces and displacements
generated from such events. Strength design concepts are yielding to more elegant
and efficient energy dissipative devices such as large-scale viscous dampers. The
reliance on these devices to dissipate energy stemming from wind and seismic
occurrences makes them integral components to the success of the design to withstand
such events. Failure of a viscous damper can portend potentially catastrophic
localized or large-scale system failure, as the adjoining members are sized based on
the energy absorbed by the dampers. Given the criticality of the damper elements to
the success of the design strategies being implemented on these large structures, a
means of evaluating their in-situ health is imperative.