| In order to find out an approach to performance monitoring and assessment during operation, also to establish a stable efficient health monitoring system on cable-stayed bridges, some basic theory and technology was studied and summarized. Based on the existing problems of this area, this dissertation focus on the following aspectes:1、Considering that a lot of sensors needed on cable-stayed bridges, network topological structure of sensors is optimized. The network is supposed to be a comprehensive bus type combined with star-shape network. Layout plan of field bus type fiber sensor system was studied, especially the optimum proposal and wireless transmission technology.2、To find out the monitoring points of cable nonlinear vibration, parameter analysis of it was carried out. Moreover, nonlinear internal resonance, parametric vibration and vortex induced oscillation were analyzed and calculated. Based on the calculation results, we proposed a method to evaluate the cable system stability under vortex induced oscillation. This method is supposed to be effective in assessing cable system performance and predicting the risk of cable oscillation.3、Based on an existing data analysis software, fatigue load spectrum is analyzed statistically through rain flow method. Fatigue assessment of structure was carried out under fatigue load spectrum. When test data is insufficient, fitting analysis was supposed to be used. However, statistic method is first option when test data is sufficient in order to avoid analysis error caused by fitting method due to neglecting the influence of some important isolate peak data.4、Cable rusting problem is an very important factor affecting structure’s durability and safety. Considering that cable rusting monitoring on bridge is still in kind of primary stage, an integrated monitoring scheme was proposed, which contains three main parts, video monitoring in anchorage area, acoustic emission monitoring in cable ending area, self-driven magnetic leakage monitoring in middle span of cable.5、Considering the problem of calculation efficiency of CWT, discrete pattern of the method is studied. So far traditional DWT method is most used in term of repeatedly calculating discrete point product. A new arithmetic which contains translation parameter b is proposed. Consequently, a simple calculating program has been written based on Maple software. Then, a selected load time-history had been put into the cable stayed bridge model. Model response to time histories was transformed by DWT program. The analysis results show that DWT inherits all advantages of CWT, and is effective to identify the damage information in response histories. Additionally, DWT has an apparent advantage in terms of calculation efficiency.6、Considering that there were a lot of failure modes in cable-stayed bridges, this dissertation focused on several typical modes, and pointed out cable stress failure, main beam deflection and stress failures were basic modes. Monte Carlo random selection method and multiple parameter response surface analysis method were used comprehensively to calculate the structural reliability. Based on damage detection information, structural reliability under damage was studied. |
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