Sensor Placement and Structural Damage Evaluation by Improved Generalized Flexibility

Abstract

The technology of damage evaluation based on data collected by sensors has become an important topic in the field of structural engineering This paper presents an improved generalized flexibility method for sensor placement and damage evaluation. Compared with the existing methods, the main improvements of the proposed method lie in three aspects. The first one is to replace mass-normalized mode shapes with arbitrary-scaled mode shapes since that only the latter can be obtained in modal testing under ambient excitation. The second one is to combine the generalized flexibility sensitivity with the frequency sensitivity to obtain more equations. The third one is to use a new regularized generalized inverse technique for computing the unknowns more accurately. Sensor placement based on the improved generalized flexibility method can be divided into three steps. Firstly, the number of sensors can be predicted by a simple formula derived by the principle of the number of equations should close to the number of unknowns as far as possible. Secondly, the key components of the whole structure are determined based on their contributions to the global generalized flexibility change. Thirdly, the sensor positions can be obtained according to the common nodes of those key components. Overall, the proposed method is simple and convenient since it only needs environment excitation and a few sensors. The results of numerical and experimental examples show that the proposed method can successfully evaluate structural damage with a few sensor signals.