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Title: Multi-scale modelling of long-span bridges for health assessment in structural health monitoring
Authors: Yu, Yang
Degree: Ph.D.
Issue Date: 2012
Abstract: Nowadays long-span bridges are usually modeled in different length scale levels for various research purposes. An accurate model should concurrently use the different theories at the respective scale level. The work described in this thesis aims to develop the effective strategies and methodologies for multi-scale finite element modeling of long-span steel bridges for health assessment and demonstrate its efficiency through analytical and experimental case studies as well as the practical engineering applications. The strategy and methodology of multi-scale modeling is successfully proposed and numerically implemented using mixed dimensional coupling through multi-point constraint equations. The reduced-scale specimen of the longitudinal steel truss has been studied in analytical computation and laboratory test. The comparison between the calculated results by different models and measurements data as well as the analytical results comparison with ones by other modeling methods suggest the proposed multi-scale model is the most efficient and accurate. All the strategies and implementation methods have been generalized and considered as applicable to full-scale long-span bridge structure. As an actual engineering application, a multi-scale model of long-span bridge of Tsing Ma Bridge is then developed by incorporating local detailed model of concerned location into structural global model based on proposed multi-scale modeling strategy. Structural global response at component scale and the hot-spot stress distribution of critical locations at local scale are then obtained simultaneously that can be used for structural health assessment and damage-related analyses. After performing sensitivity-based model updating and verification, the comparison results indicates that the developed multi-scale model is superior as compared to traditional two-step analyzing method. To demonstrate the developed multi-scale model can be further extended for nonlinear analysis, the linear and nonlinear seismic responses of the bridge under El-Centro ground motion are investigated considering geometric nonlinearity and bilinear hysteretic constitutive model. There are no universal principles to describe the influence pattern of traveling wave, so such effects should be specifically investigated for an individual bridge. The implementation schemes for nonlinear damage-related analyzing procedures are finally explored and outlined by introducing a nonlinear computing algorithm of constitutive equations combined with proper damage laws to consider the structural deterioration process.
Subjects: Long-span bridges.
Structural health monitoring.
Hong Kong Polytechnic University -- Dissertations
Pages: 1 v. (various pagings) : ill. (some col.) ; 30 cm.
Appears in Collections:Thesis

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