Paper published in a journal (Scientific congresses, symposiums and conference proceedings)
Some remarks on the influence of temperature-variations, non-linearities, repeatability and ageing on modal-analysis for structural health monitoring of real bridges
structural health monitoring; temperature influence; modal analysis
Abstract :
[en] Structural Health Monitoring (SHM) intends to identify damage by changes of characteristics as for instance the modal parameters. The eigenfrequencies, mode-shapes and damping-values are either directly used as damage indicators or the changes of derived parameters are analysed, such as e.g. flexibilities or updated finite element models. One common way is a ontinuous monitoring under environmental excitation forces, such as wind or traffic, i.e. the so-called output-only modal analysis. Alternatively, a forced measured external excitation in distinct time-intervals may be used for input-output modal analysis. Both methods are limited by the precision or the repeatability under real-life conditions at site. The paper will summarize everal field tests of artificially step by step damaged bridges prior to their final demolishment and it will show the changes of eigenfrequencies due to induced artificial damage. Additionally, some results of a monitoring campaign of a healthy bridge in Luxembourg are presented. Reinforced concrete shows non-linear behaviour in the sense that modal parameters depend on the excitation force amplitude, i.e. higher forces lead often to lower eigenfrequencies than smaller forces. Furthermore, the temperature of real bridges is neither constant in space nor in time, while for instance the stiffness of asphalt is strongly dependant on it. Finally, ageing as uch can also change a bridge’s stiffness and its modal parameters, e.g. because creep and hrinkage of concrete or ageing of elastomeric bearing pads influence their modulus of elasticity. These effects cannot be considered as damage, though they influence the measurement of modal parameters and hinder damage detection.
Research center :
Faculty of Science, Technology and Communication, Engineering Sciences
Disciplines :
Civil engineering
Author, co-author :
Maas, Stefan ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit
Schommer, Sebastian ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit
Nguyen, Viet Ha ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit
Waldmann, Danièle ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit
Mahowald, Jean ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit
Zürbes, Arno
External co-authors :
yes
Language :
English
Title :
Some remarks on the influence of temperature-variations, non-linearities, repeatability and ageing on modal-analysis for structural health monitoring of real bridges
Publication date :
19 October 2015
Event name :
EVACES’15, 6th International Conference on Experimental Vibration Analysis for Civil Engineering Structures