Research On Monitoring And Condition Assessments Of Self-anchored Suspension Bridge With Single Tower

Self-anchored suspension bridge with single tower is a new type bridge in recent years, and it has been developed rapidly at home and abroad. Because of its complicated structure form and less monitoring on this type of bridge, this paper systemically researched on monitoring and evaluation of self-anchored suspension bridge during the operation of Nanjing Jiangxinzhou Bridge. The main work of this paper is as follows:1. Analysis of the influence factors of structural safety and the contents of safety monitoring.According to the structural characteristics of self-anchored suspension bridge, this paper analyzed the safety factors of the main structure parts including cable crane system, the main tower structure, stiffening girder structure. On the basis of the analysis of structural safety factors, the paper determined the contents of safety monitoring and regular inspections of self-anchored suspension bridge.2. Research on monitoring methods of bridge in operation periodFor Nanjing Jiangxinzhou Bridge, the static and dynamic sensor arrangement methods were studied. Based on the analysis of the moving load and considering the most unfavorable combination of loads, the paper determined the maximum response locations of main cable force, the stress of the main girder, the vertical displacement of girder, the main tower bias. Using wireless acceleration sensor to test vibration frequency of boom-plane, the paper investigated the factors and methods of the internal force calculation. Through eigenvalue analysis, the paper identified the monitoring programs of vertical vibration mode only for main span girder. Finally, the joint algorithm of Fisher information matrix and MAC matrix was proposed to optimize the measuring points of vertical vibration on the main span girder.3. Responses analysis of main components of self-anchored suspension bridge with single tower in operation periodUsing the periodic monitoring dates, the responses of the strain on the main beam, main beam vertical displacement, axial force main cable, sling forces were analyzed in operation period. The results show:the main beam strain correlated with the ambient temperature positively; the amplitude change of the vertical displacement in measuring points of the main beam was small in four quarters, and the changes of same section in upstream and downstream tended to be the same; Main cable axial force kept stable in four quarters; Sling force was affected by temperature obviously, and the error of sling force calculation was a bit large in low temperature seasons.4. Research on comprehensive evaluation method based on fuzzy AHP analyticIn order to assess the effects of different reaction of main component more effectively, the pair of fuzzy judgment matrix was introduced, and then the Analog Solving Method was used to solve the weight vectors; Through classified the underlying indexes, the dimensionless "1" processing methods were introduced to make each index comparable; The concept of variable weighting coefficient was introduced to consider the impact on the overall assessment results when the evaluation had serious defects; Based on the above analysis, comprehensive evaluation model with multi-level and multi-objective of Jiangxinzhou bridge was established, considering the affects of the main tower, the main cable, boom, stiffening girder, foundation of tower and ancillary facilities; Finally, the fuzzy AHP with variable weights had been effectively applied in the assessment of the actual state of Jiangxinzhou Bridge.