Distributed Displacement Response Investigation Technique for Bridge Structures Using Smartphones

The vertical displacement of a cross section of a bridge has a close correlation with the carrying capacity and the ability to resist dynamic loads. Therefore it has been one of the most important parameters for structural health monitoring and safety assessment. Moreover, when a natural disaster such as a hurricane or an earthquake occurs, a large number of bridges will be affected. To evaluate safety performance and investigate failures preliminarily, rapid inspections of displacement are essential for bridges. This paper presents a bridge distributed displacement investigation technique using smartphones. This smartphone-based technique is a beneficial complement to conventional structural health monitoring techniques for its cost efficiency and operability. Based on photogrammetry technology, an algorithm is used to develop an app called D-Viewer. Multipoint dynamic displacement monitoring is implemented synchronously using smartphones. Experiments conducted in the laboratory with reduced-scale models show that this technique is able to monitor the distributed displacement response with reasonable precision. Through data processing, performance of bridges will be evaluated. Low cost and convenience of this technique make it possible for anyone to monitor or inspect the displacement of every short and medium span bridge preliminarily.