Bridge displacement is the most basic evaluation index of the health status of a bridge structure. The existing measurement methods for bridge displacement basically fail to realize long-term and real-time dynamic monitoring of bridge structures, because of the low degree of automation and the insufficient precision, causing bottlenecks and restriction. To solve this problem, we proposed a bridge displacement monitoring system based on laser projection-sensing technology. First, the laser spot recognition method was studied. Second, the software for the displacement monitoring system was developed. Finally, a series of experiments using this system were conducted, and the results show that such a system has high measurement accuracy and speed. We aim to develop a low-cost, high-accuracy and long-term monitoring method for bridge displacement based on these preliminary efforts.

Vibration testing is an effective approach to obtaining the dynamic parameters of a bridge and evaluating its state of health. It is carried out mainly on the basis of wired or wireless sensor networks, which consist of expensive sensors and data-acquisition and -transmission systems, and professional installation is required. Integrated with networks, sensors, and storage capability, smartphones can be convenient to use for vibration testing, and the dependence on professional installation can be reduced. Toward this end, an innovative smartphone-based mobile testing method is proposed and demonstrated in this paper. First, software with two acquisition modes for the iPhone 4s was developed. Second, smartphone-based cable-force tests were performed in the laboratory to validate the feasibility of the proposed technique. Last, the technique was applied to the Hualu and Sifangtai bridges to validate the feasibility of using this technique on real bridges. The results confirm the convenience and eff...

Offshore design and construction is much more difficult than land-based design and construction, particularly due to hoisting operations. Real-time monitoring of the orientation and movement of a hoisted structure is thus required for operators’ safety. In recent years, rapid development of the smart-phone commercial market has offered the possibility that everyone can carry a mini personal computer that is integrated with sensors, an operating system and communication system that can act as an effective aid for cyber-physical systems (CPS) research. In this paper, a CPS for hoisting monitoring using smartphones was proposed, including a phone collector, a controller and a server. This system uses smartphones equipped with internal sensors to obtain girder movement information, which will be uploaded to a server, then returned to controller users. An alarming system will be provided on the controller phone once the returned data exceeds a threshold. The proposed monitoring system is used to monitor the movement and orientation of a girder during hoisting on a cross-sea bridge in real time. The results show the convenience and feasibility of the proposed system.

Bridge is an important part of modern transportation systems and deflection is an important index for bridge’s safety evaluation. In this paper, a method of deflection measurement using Wireless MEMS Inclination Sensor Systems (WMISS) is presented and validated. Firstly, based on various bridge deflection measuring methods, the method of deflection measurement using inclination parameter is introduced. Secondly, a low-power wireless inclination sensor based on 3D-MEMS SCA60 inclinometer is designed using modularization way, and this kind of wireless sensor loaded with ZigBee/IEEE 802.15.4 MAC protocol stack can self-organize wireless sensor network, measure the angle value and send the data to the coordinator. Then the deflection curve is displayed on PC. Finally, deflection measurement experiments are conducted on a bridge model and Beida Bridge. The experimental results show that, the presented deflection measurement method is feasible, practical and reliable; the wireless inclination sensor is easy to operate with no lines, and has extensive and broad application prospects.