Free-Interface Modal Synthesis Based Substructural Damage Detection Method

Shanghong Chen,Jiexin Yu,Ai Qi,Wei Lin

doi:10.1155/2014/741697

Abstract

Free-interface modal synthesis method is applied to civil structure, and a substructure method is proposed by introducing the method into global sensitivity method. The substructure expression of the derivatives of eigenvalues and eigenvectors with respect to elemental parameters is obtained. The accuracy of the application of free-interface modal synthesis method is evaluated with different retained modes in substructure, and then the effectiveness of the proposed substructure sensitivity method is illustrated through an 11-storey building under both single- and multidamage cases. Both the damage locations and the extent can be effectively identified. By comparing it with the identical results of global sensitivity method, the proposed method can be faster in detecting the damage location and more stable under multidamage cases. Since this substructure sensitivity method only needs to update sensitivity matrix in the substructure with relative small number of DOFs, it may save much computation effort and become more efficient.

Highlights

To ensure the safety of large-scale civil infrastructures, more and more health monitoring systems are adopted to evaluate health condition and to prevent sudden failure due to accumulation of component damages [1,2,3,4,5]
As it comes to civil structures, their finite element model (FEM) usually have large number of DOFs, which will result in equations with huge dimension during the model updating and damage detection procedure
A free-interface modal synthesis method is applied to civil structures, and, by introducing to the sensitivity method, a free-interface modal synthesis based substructure sensitivity method is proposed for damage detection

Summary

Introduction

To ensure the safety of large-scale civil infrastructures, more and more health monitoring systems are adopted to evaluate health condition and to prevent sudden failure due to accumulation of component damages [1,2,3,4,5]. By comparing the output change such as natural frequency, mode shape, mode shape curvature, and flexibility changes due to structural aging or adverse environmental effects, it is expected that the system should be able to detect local damages and give maintenance advices [10,11,12] As it comes to civil structures, their FEMs usually have large number of DOFs, which will result in equations with huge dimension during the model updating and damage detection procedure. The derivatives of eigenvalue and eigenvector with respect to system parameters will be calculated with the substructure method With only those factors within certain substructures having nonzero value, this method is supposed to require few computation efforts and higher efficiency in damage detection. In order to maintain the accuracy during damage detection, the accuracy of modal synthesis method will be first discussed and the damage detection ability of the proposed method will be verified under several damage cases

Free-Interface Modal Synthesis

Modal Synthesis Based Substructure Damage Identification

Numerical Studies

Findings

Concluding Remarks