Thermal Environmental Effects on Modal Parameters and Health Monitoring of Bridge Structures

摘要

Often changes in the frequencies extracted from the vibration response are used for the detection ofrndamage. However, these structural characteristics are also affected by the outside thermalrnenvonment; this effect could be large enough to mask the changes caused by the damage. So it isrnimportant to understand and predict the effect of the environmental variations on theserncharacteristics to separate them from those caused by the damage. In this paper, we examine therntrends in the frequencies variations of a reinforced concrete box girder bridge structure subjected torna nine-year long record of measured temperature, radiation, and wind speed. It is observed that thernmajor trends in the frequency variations are parallel to the major trends in thermal environment.rnThe paper then presents and validates an identification approach to estimate the system frequenciesrndirectly from a few measured temperature values without a detailed finite element analysis.