Increasing Resilience in Civil Structures Using Smart Damping Technology

Date of Completion

January 2012

Keywords

Engineering, Civil|Engineering, Mechanical

Degree

Ph.D.

Abstract

Highway bridges are a significant and critical component of the civil infrastructure. However, they are continuously approaching or exceeding their design life and are increasingly being classified as structurally deficient. There exists a current need in our nation to address the deteriorating integrity of our infrastructure. The service life of highway bridges can be extended through the innovative application of structural control to reduce the peak stress in the critical elements of the bridge due to heavy truck traffic. ^ In this dissertation, Magneto-Rheological (MR) fluid damper as a particularly promising type of semiactive control device is evaluated for this purpose. To fully utilize the unique characteristics of the MR damper, an accurate model needed to be developed for use in control design and analysis. In order to better utilize a new type of experimental testing method, called Real-Time Hybrid Simulation (RTHS), to validate the analytical study, relative performance of four predominant 200 kN MR damper models, namely hyperbolic tangent, Bouc-Wen, viscous plus Dahl and algebraic, is examined for RTHS pretesting. ^ Then a high fidelity fully-dynamic MR damper model, which includes a model of the pulse-width modulated power amplifier providing current to the damper, a model of the inductance of the large-scale 200 kN MR dampers coils and surrounding MR fluid, and a hyperbolic tangent model of the controllable force behavior of the MR damper is developed to improve the performance. With the MR damper model developed, an analytical study of evaluating the performance of MR damper controlled highway bridge under five-axle truck loading by using a simplified bridge model is conducted. The results are experimental verified by using real-time hybrid testing at the Lehigh University Network for Earthquake Engineering Simulation (NEES) facility. To resolve the size limitation of numerical component in the RTHS and include more detailed bridge model in the study, a new developed Convolution Integral Method is adopted, experimental validated and used for evaluating the MR damper's performance in reducing undesired truck induced vibration. Besides daily traffic loadings, the transportation infrastructure is also subjected to many natural and man-made hazards. To increase the resilience of the infrastructure, an innovative symbiotic system combing structural control and structural health monitoring is proposed, which the integrated system leverages the individual system and provides the benefits that won't be able to achieve for single system acting alone. ^

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