Local scour is one of the major factors for bridge failure. Scour failures tend to occur suddenly and without prior warning or sign of distress to the structure. Two types of real-time monitoring systems for bridge scour, using fiber Bragg grating (FBG) sensors, have been developed and tested in the laboratory. These FBG scour-monitoring systems can measure both the processes of scouring/deposition and the variations of water level. Several experimental runs have been conducted in the flume to demonstrate the applicability of the FBG systems. The experimental results indicate that the real-time monitoring system has the potential for further applications in the field.
Failures of bridges that span a waterway often result from scour and channel instability near the bridge foundations. The Houfeng
Bridge, which crosses the Da-Chia River in central Taiwan, collapsed in the 2008 typhoon flood event. On the basis of the historical records
and survey of related data just after the collapse of the bridge, a methodology for the assessment of scour depth, including long-term general
scour caused by earthquake and impinging jet scour generated by a concrete encased pipeline, is illustrated in the present study. The proposed
method provides reasonable estimates for various scour components, which implies that before constructing a new or rebuilding an old bridge,
one should use proper methodology and formulas to evaluate the scour potential and improve the bridge design, especially for bridges that are
founded around the Houfeng Bridge. This case study also highlights the important effect of long-term general scour on bridge stability. In
addition, a lesson is learned from this case study regarding the importance of bridge operation
The temperature dependence of the current–voltage characteristics of Ba0.5Sr0.5TiO3 (BST) thin-film capacitors was studied from 300 to 433 K. An Au/BST/Pt/Ti/SiO2/Si structure was used. The BST films were deposited by rf magnetron sputtering. The conduction current was dominated by Schottky emission at room temperature and by Poole–Frenkel emission above 403 K. The dominant conduction mechanism changed from Schottky emission to Poole–Frenkel emission in the temperature range from 373 to 403 K. The BST/Pt and the BST/Au Schottky barrier heights were found to be 0.88 and 0.72 eV, respectively. The trap energy level in BST was 0.83 eV.
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