Wireless monitoring of concrete structures using Micro-Electro-Mechanical Sensors (MEMS)

The inspection of building structures and especially of bridges is mainly done visually nowadays. Therefore, the condition of the structure is examined from the surface and the interpretation and assessment is based on the level of experience of the engineers. An approach to continuous structural health monitoring techniques based on wireless sensor networks is presented, which provide data from the inside of a structure to better understand its structural performance and to predict its durability and remaining life time. It is based on a new kind of sensors using MEMS (Micro-Electro-Mechanical-Systems) techniques. Low-priced sensors are an essential requirement for monitoring systems in order to be accepted by the industry. Embedded wireless communication techniques will reduce the application and maintenance costs significantly. Besides sensors, signal recording and analysis techniques need powerful algorithms to process and compress the immense amount of data. Algorithms for data compression based on neural network techniques and localization of damaged areas by sensor array techniques have to be developed. Although the development costs of such a system are relatively high, the target price for the monitoring device should be no more than several thousand Euros, depending on the size of the structure and the number of sensors necessary to cover the most important parts of the structure. While such a system is scalable and adjustable to different types of bridges, it is expected that its acceptance is high at least for bridges of higher value or bridges with critical defects. As a first step, only critical parts of the structure will be implemented in this monitoring approach. The described technique will work as a maintenance free monitoring system sending data (alarm data) via internet to a data center or alarm messages per SMS automatically to the monitoring engineer. This cost-effective approach will be interesting for bridge owners respect to larger or important bridges, respectively.