As is well known, bridges, as important carriers of public transportation, play a vital role in the smooth operation of regional transportation and the development of social economy. With the leapfrog development of the social economy, the traffic flow on bridges has increased rapidly, and the impact of safety hazards on bridges has intensified. Bridges are damaged and diseased due to factors such as harsh usage environments, the effect of loads, and excessive service life, which pose a threat to the safety of bridges and may lead to bridge accidents.
In recent years, bridge safety accidents have occurred frequently, causing great social impacts and serious consequences for people's lives and safety. China is a large bridge-building country, and large bridges are important nodes of the main traffic arteries, having a significant impact on the development of transportation. During the long-term use process, due to environmental erosion, material aging, the increasing traffic volume, and the continuous increase in the number of heavy-duty and overweight vehicles crossing the bridge, the bridge structure is damaged and its functions are degraded. As a result, the ability to resist natural disasters and even the effects of the normal environment decreases, and in extreme cases, disastrous accidents may occur, causing heavy casualties and property losses. Therefore, it is particularly important to conduct automated monitoring and diagnosis of the structural performance of bridges, and to carry out damage assessment and safety early warning in a timely manner.
The main problems currently faced by bridges are as follows:
(1) Bridge instability occurs from time to time. During the construction and use of bridges, due to the erosion of the environment and harmful substances, the effects of vehicles, wind, earthquakes, human factors, etc., as well as the continuous degradation of the material's own performance, the bridge structure will suffer damage and deterioration to varying degrees. In extreme cases, it is likely to lead to disastrous accidents, resulting in heavy casualties and property losses.
(2) Overloading and over-limit are difficult to prohibit. With heavy traffic on bridges, the problem of overloading and over-limit persists. This will increase the fatigue stress amplitude of the bridge, intensify the damage to the bridge structure, and when it reaches a certain extent, it will cause structural damage, affecting the safety and service life of the bridge and greatly shortening the lifespan of the bridge.

(3) The means of maintenance and management need to be improved. The maintenance and management work mainly relies on manual technical means such as "daily inspections and regular inspections as the mainstay, supplemented by special inspections". The inspection cycle is long, and it will inevitably have an impact on the normal traffic operation.

Ruhr IoT has been deeply engaged in the field of safety monitoring for many years and owns a variety of intelligent hardware devices, including the Visual Series, Beidou Series, Piezoelectric Series, and Acceleration Series. Among them, the visual deformation instrument is a high-precision, non-contact intelligent sensing device. This device is not restricted by geographical location and is generally deployed in a stable area away from the object to be monitored, with a high degree of flexibility. It can also achieve automated real-time monitoring. New non-contact sensing devices represented by the visual deformation instrument have made up for some inherent shortcomings of traditional contact sensing devices. During the monitoring process in scenarios such as bridges, tunnels, high slopes, collapses, cultural relics and ancient buildings, and industry, they have advantages such as long-distance monitoring, multi-target monitoring, non-destructive monitoring, and low comprehensive cost.

Product Picture of the Visual Deformation Instrument

The visual deformation instrument of Ruhr IoT has numerous successful cases in the transportation field. Among them, in the Yuhang Bridge Group Project, taking eighteen bridges within Yuhang District as the pilot, a real-time monitoring and sensing network for the bridge group was established. The construction of an urban safety operation supervision platform with the safety monitoring of the bridge group as the main content was carried out, forming a comprehensive, all-round, systematic, and modern infrastructure safety operation management system with Yuhang characteristics, leading as a demonstration and setting a model.
Among these bridges, Maoshan Bridge is a double-lane, two-way, six-lane river-crossing bridge located on G104 Jinglan Line in the Pingyao area of Yuhang District, Hangzhou City, Zhejiang Province. The upper structure is composed of slab beams, and the lower structure is column piers. The result of the regular bridge inspection in 2021 showed that it was a Class 2 bridge. In this project, a visual deformation monitoring system was adopted. A total of 12 targets were arranged at the 1L/4, 1L/2, and 3L/4 positions of the main span. Four visual deformation instruments were used to observe the targets, and online real-time monitoring of the deflection and horizontal displacement of the bridge was carried out.

The visual deformation instrument mainly conducts static monitoring. After several years of technological accumulation, it has completed the pilot verification of deformation displacement (such as two-dimensional/three-dimensional static displacement changes of structural bodies, road subsidence, static and dynamic deflection of bridges, track deformation, tunnel convergence, etc.). With the support of the temperature compensation and anomaly algorithms, the monitored data has become more stable.
At present, the visual deformation instrument has made significant progress in the field of bridge monitoring. It can not only improve the accuracy and efficiency of bridge monitoring but also greatly reduce the investment of human and material resources. It is believed that with the continuous advancement and improvement of technology, the visual deformation instrument will be able to provide safety monitoring services for more scenarios.