Investigation of Seasonal Variations of Dynamic Characteristics of a Concrete Bridge by Employing a Wireless Acceleration Sensor Network System

Abstract

In this study, a fundamental application of a wireless acceleration sensor network system was carried out by conducting two bridge vibration experiments in autumn and winter. Seasonal effects on the dynamic characteristics of a multispan ballasted prestressed concrete railway bridge were investigated by employing a wireless acceleration sensor network system as a basic study of structural health monitoring technology. The dynamic parameters of every single span, such as natural frequencies, damping ratios, and mode shapes, were determined from free damped vibration, which was caused by human jumping excitation. Owning to the excitation pattern limitation, three modes were obtained in the experiments. A three-dimensional (3D) finite element (FE) model was made to show the rationality of the experimental result. Comparison of the autumn and winter experimental results showed that the natural frequencies of the bridge were significantly higher in winter than in autumn. The frozen ballast and frost on the deck and walkway were revealed to be reasonable explanations for this phenomenon. Meanwhile, the variations of damping ratios were not as simple as those of the natural frequencies. No variation regularity of damping ratios was obvious.

Long-Term Investigations of Dynamic Behavior of a Pre-Stressed Concrete Ballasted Railway Bridge

“…12, the natural frequencies in each mode from the No.1 to No.8 experiments show a clear seasonal variation tendency that there are two local maximum peaks of the natural frequencies in the Februaries of 2016 and 2017. To find reasonable explanations for this phenomenon, we have carried out a series of investigations [16,27,28]. Because Hokkaido is in the northern hemisphere, the season in February is winter.…”

“…Ubertini et al [14] investigated the environmental effects on a tower and proposed a method to remove the effect. For the ballasted railway bridges, by monitoring the dynamic behavior of the bridge, the effect of frozen ballasts on the natural frequencies is found [15,16]. To briefly explain the mechanism of the environmental effect on the modal properties, the modulus of elasticity of the construction materials varies owing to environmental changes.…”

Bridge Damage Identification by Ground-based Synthetic Aperture Radar Using Blind Source Separation and Noise Reduction Technology

“…The results of a simulation experiment on the design of an aluminum bridge showed that this method could identify the abnormal changes in the bridge. (11) The natural frequency of a bridge can be selected as an indicator for bridge damage identification, (12) which has the advantage of easy measurement. Mode recognition can be used for this method.…”