Research On The Monitoring System Of Dynamic Characteristics For Dafoshi Changjiang Bridge

It is the frontiers of bridge construction to evaluate health states and establish safety database of long-span bridges through monitoring structural dynamic behavior, material strains, deflection and temperature variation in order to ensure their safety in operation, more appropriately service and manage, and more efficiently discover disease problems at early stage. Based on the engineering practice of the Dafosi Changjing Bridge, a comparative research on software and hardware realization in health monitoring system for bridge structural dynamic behavior is conducted. The dynamical characteristics of the Dafosi Changjiang Bridge are calculated using MS-NASTRAN based on an original three-beam model. Then structural dynamic characteristics of the bridge are also tried to be investigated based on vibration signal processing and monitoring, and a rounded measuring and monitoring system of structural dynamics for large scale bridge structures is constructed by using the up-to-today techiniques in the fields of sensor device, signal proceesing, and computer communication. With the measuring and monitoring system under environmental excitation, dynamic behavior of large scale bridge structures with super-low frequency could be monitored, and evaluation of health states for the Dafosi Changjiang Bridge is perfectly put into effect. Based on the research in this thesis, structural dynamic calculation of the large scale cable-stayed bridge is improved based on the three-beam model, and the distribution of acceleration transducers is more reasonable according to the calculated resulte of dynamic characteristics of the bridge. Moreover, super-low frequency vibration of large scale bridge structrues is successfully measured based on new technical approaches such as particular acceleration transducers, unique sensors mounting, special data acquisition and transmission. Further, some important problems such as double-pass and bidirection of instruction and data, data storage and processing, 3D display of structural dynamic behavior are effectively solved.