Application of Optoelectronic Liquid Lever Sensor in Urban Bridges Deflection Monitoring

Abstract

The deflection which reflects the bridge linear variety is an important parameter for the evaluation of bridge safety. According to the structural characteristics of urban bridges, the connected pipe optoelectronic liquid level sensor system is a novel kind of sensor for detecting the connected pipe liquid level, which can be applied for multipoint, long-period, online, remote, automatic measurement of bridge deflection, it is not affected by the dust, humidity and fog in the urban bridge health monitoring and maintenance. At present, the system has been integrated and applied in the project of main roads bridge Online Safety Monitoring Management System in Hangzhou (Phase II), a web-based urban bridge cluster monitoring system have been established since 2007. According to a tied arch bridge case studies, the measuring data show that the system not only can accurately collect the bridge normal deflection information and variety, but also successfully monitored the structural responses due to the Wenchuan earthquake on May 12, 2008. About two-minute abrupt changes in displacement amplitude were observed in the measured signals starting at 14:37, about 9 minutes later than the earthquake’s occurring. The results shows, it is an effective method for the real-time monitoring of urban bridge deflection.

Concise Historic Overview of Strain Sensors Used in the Monitoring of Civil Structures: The First One Hundred Years

“…As opposed to stresses, deflections can be directly monitored in real-life settings using a variety of contact or non-contact sensors. Examples of the former are linear variable differential transformers—LVDTs and hydrostatic systems (e.g., [ 13 , 14 ]), and examples of the latter are cameras (e.g., [ 15 , 16 ]), global positioning system—GPS (e.g., [ 17 , 18 ]), laser-based sensors (e.g., [ 19 , 20 ]), and radar-based sensors (e.g., [ 21 ]). However, even though these sensors enable direct monitoring of deflections, their implementation in real-life settings faces significant challenges that render them impractical for long-term monitoring: they require stable reference points, an unobstructed line of sight, and clear targets (e.g., [ 22 , 23 ]).…”

Error in the determination of the deformed shape of prismatic beams using the double integration of curvature

“…Direct measurements are performed using for example linear variable differential transformers (LVDTs), hydrostatic systems (Burdet 1993, Li et al 2012, global positioning system (Roberts et al 2004, Figurski et al 2007, radars (Gentile and Bernardini 2010), lasers (Psimoulis andStiros 2007, Fang andYunfei 2012), and cameras (Jauregui et al 2003, Tian et al 2013. The main advantages of direct deformation measurements are that they can be used on many different types of structures and no knowledge of boundary conditions is required.…”