Technical Studies


Development of Bridge Failure Alarm System (2)

Bridges are critical facilities in the transportation system. However, due to limited manpower and budget, it is impossible to keep all bridges under full scrutiny during flooding events. Besides continuing research on bridge health monitoring, it is equally important to devise economical, simplified, and durable measure for real time bridge failure warning to reduce possible losses due to bridge collapse. Unlike bridge health monitoring which focuses on measurements such as deformation, vibration, and bridge scour, this study focuses on developing real-time bridge failure warning system as a last resort to protect bridge users. The study reviewed existing methods and proposed three prototypes of bridge failure warning systems, including 1) simple open circuit detector, 2) extension detection device, and 3) Time Domain Reflectometry (TDR) method. Extension detection device and TDR method were first proof tested and modified in the laboratory, followed by performance verification with field testing and full-scale bridge failure test. The experimental results show that the extension detection device can reliably provide real-time failure warning on site and inform the management agencies the rough location of failure. TDR method can provide precise location of failure and involves only cable installation, but the response time (a couple of seconds) should be further improved by improving the data acquisition method. Both extension detection device and TDR method can easily adapted to be applied in landslide, debris flow, and structure integrity monitoring