Identification of the Desired Sensor for Detecting Damage in Concrete Bridge Piers using Modified Matrix Subtraction Method and Tensor Method

Modified Matrix Subtraction Method (MMSM) and Tensor Method(TM) are simple but useful methods for detecting damage in concrete piers of bridges. In the methods, square time-frequency representation was used for the first time to damage detection in the bridges. In signal procedures, damage diagnosis becomes possible with structural monitoring which sensors are used for measuring the structural behavior. Considering the variety of sensors, in accordance with the used method to detect damage, it is necessary, suitable sensor for measuring structural behavior is determined and sensitivity of the used method to recorded signals is investigated. In this research, exciting force and time-frequency representation algorithm was used to detect damage and determine its location. Besides, analytical models of W180 and MGR bridges were selected as the structural samples. Also sensors including displacement gauge, speedometer and accelerometer for detecting damage in concrete piers of bridges using MMSM and TM were evaluated and optimal signal type which is much compatible with the proposed methods and algorithm were assessed and identified. According to performed calculations, using response signals recorded by displacement gauges and applying MMSM and TM, better results were obtained when compared to speedometer and accelerometer were used. When displacement gauges were used, the damaged piers were correctly identified in all of the cases. However, using signals recorded by speedometer and accelerometer, damaged piers were reported correctly in 88.9% and 94.4% of the cases, respectively. Furthermore, the effects of the distance of the sensor locations from the affected area and their impact on the results were studied. In accordance with the calculated results, by reducing the distance between mounting location of the sensors from the damaged area, ability and accuracy of MMSM and TM were increased.