Safety Monitoring Of Large-Scale Bridges In Shanghai

With the extensive building of large-scale bridges, more and more attention has been paid to the safety of the bridge structures. Shanghai is leading in the construction of long span and large scale bridges in China. But up to now there is no scientific and systematic method for the monitoring and administrating of the existing bridges.In the present thesis, based on both transportation and environment characteristics of Shanghai, the key points of the monitoring system for the large-scale bridges, primarily cable-stayed bridges, are presented, and the types of structuaal damage and the monitoring methods are summarized.In safety monitoring of large-scale bridges, two problems must be resolved: a) the monitored indexes are not enough sensitive to damages. b).the reliability of monitor system itself.In most of automatic monitoring methods, the dynamic behavior of a structure is always taken as the most important consideration. In the present thesis, the sensitivity of the dynamic features to damages, environment and boundary conditions are analyzed from member level and structural level as needed. The results proved that the dynamic features are not sensitive enough to damage and uaually are covered by the influence of other factors. Therefore, in this case, the monitored terms should be in global vision and reasonable. It seems that the automatic monitoring methods still need to be cooperated by manual inspecting.During monitoring process, it is inevitable to renew the existing sensors owing to the relatively short life time of the monitoring sensors. It is very urgent to develop a reasonable process for the substitution of the embedded monitoring sensors and to keep data continuously and smoothly. These problems, to some extent, have been resolved in the present thesis. Finally, discussion is presented on how to build a human-machine system for a realistic monitoring system.