| dc.description.abstract | Bridges in Taiwan are currently facing three major challenges, namely the deterioration, earthquakes and floods. The heavy rain was more often occurred in recently years, because of the global climate change. Therefore, the bridge health diagnostic system with measuring and analysis technique is more important for bridge management and maintenance.
The loading capacity and service life of bridges are usually impaired by reinforcement corrosion, tendon corrosion or tendon relaxation. Non-destructive tests and monitoring techniques are usually used to determine the impact of loading capacity and service life of bridges. This research has developed serval methods to measuring the deflections of bridges using in bridge loading test and bridge health monitoring system. The bending gauges are used to develop a deflection measuring system of bridges. By linking bending gauges and connecting tubes as a sensing chain, this system can measure multiple locations of deflections caused by static or dynamic load at the same time. Also, the deflections of bridges caused by tendon relaxation can be measured either.
An upgraded piezoelectric film type real-time scour monitoring sensor installed along the bridge pier is presented. The core idea of developing this scouring sensing system is based on the physical character that output voltage can be generated as the piezoelectric film is deformed by the flowing media. The piezoelectric film embedded in the soil of riverbed is undisturbed and the output voltage is much smaller than the one disturbed by the water current. From the output signals of all the piezoelectric sensors with known locations along the depth of the pier foundation, one can trace the variation of the soil/water interface before, during and after a flood. Compared with other types of scouring sensors, this piezoelectric type scouring sensor is working without power, durable, sensitive, real-time and cost effective. In this research, a signal processing technique and performance tests in laboratory of this novel piezoelectric film type scouring device are introduced first.
This research also presents a bridge monitoring and prewarning system for collapse detection. The system consists of six units: (1) Tilt and Collapse Detection Unit, (2) Power Supply Unit, (3) Image Unit, (4) Alarms Unit, (5) Communication Unit, and (6) Central Control Unit. The system monitors pier tilting as the early warning signal of bridge collapse. Once a pier tilts more than its predefined thresholds, a warning message will be sent to cell phones of relevant bridge management personnel. If any section of the bridge collapses, the system will automatically activate alert sounds and flash lights installed on the bridge, and will also display warning texts on two LED boards installed at both ends of the bridge.
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