Smart System for Detection of Earthquake Induced Damages on Bridge Piers using Phase Difference Measurement Technique

In this study, a new technique for monitoring the structural health of bridge piers, in point of view of earthquake induced damages, was introduced and then it was simulated and evaluated by the use of a scaled model of a typical bridge. This system use the detection of phase difference between two synchronous receiver nodes connected through a wireless sensor network, and is based on using an array of inexpensive high-frequency oscillator circuits (4 GHz) as wireless transmitters through placing them in the important structural positions of the bridge piers, and then receiving and analyzing the signals sent by these transmitters by two synchronous receiver nodes. The proposed monitoring system measures the changes in phase difference between two synchronous receiver nodes before and after damage (displacement or deformation); it showed an accuracy of a tenth of a millimeter in the simulations, and it also has a high reliability in monitoring the structural heath of bridge because it provides a real-time report of status of each transmitter (activated, deactivated, damaged). The proposed system has a low price compared to other SHM methods and also has a much lower volume and complexity of data processing compared with similar techniques. This study did not had any field trial, but a complete simulation by the use of an array of six transmitters (TX) and two receivers (RX) was conducted for a scaled model with six piers, and mathematical and geometrical principles and signal processing and simulation details was thoroughly examined.