Tuesday 31 January 2012

Monitoring bridges in all weathers

RDP products are frequently used to measure movements in the structure of bridges caused by the weight of traffic, environmental conditions and other factors.

Higher traffic loads and corrosion can lead to increased strain in bridge components, such as suspension cable fixing points. It is important for engineers to understand movements and loads imposed on the structure in order to predict potential problems and to maximise the safe working life of the bridge. Ageing bridge structures may be reaching overload due to the effects of increased weights and traffic volumes on steel structures that may be also weakened by corrosion or suffering early metal fatigue.

Very often the transducers used to monitor movements are installed on structures in coastal regions where the rain water must be considered saline and transducers are also exposed to chemical pollutants created by road vehicles. RDP Electronics Ltd offers many different types of products with a very high water ingress protection rating. Transducers can be supplied that are moisture resistant or fully welded for submersible applications. Thanks to a stainless steel construction these transducers are suited to operation in marine environments and also resist the corrosive effects due to winter road treatments for ice.

The LVDT monitoring approach is relatively inexpensive particularly when several points on a bridge need to be monitored, calling for long cable runs. By using a 4-20mA 2 wire loop, the wiring installation cost can be considerably reduced, as well as this offering the best interface to use with long cables for temperature drift reasons.

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