Abstract： In order to study the residual strength degradation rule of the U-ribs of orthotropic plates, the Markov process theory was adopted to assess the state change in the very long-span steel box girder suspension bridge—Xihoumen Bridge. First, the time-frequency characteristics of the long-term strain monitoring data of the steel box girder of Xihoumen Bridge were analyzed. The wavelet analysis was used to separate the stress fluctuation of the bridge deck structure caused by the change of environmental temperature. To eliminate the low amplitude stress variation caused by environmental random excitation and measurement noise, the appropriate threshold was selected for the wavelet transform coefficient at different scales. The rain-flow counting method was used to statistically analyze the monitoring data of strain under vehicle load, so that the fatigue stress range was obtained, and six fatigue stress intervals were set. Furthermore, the transition probability of the strength from the initial state to the final state was calculated from the typical S-N curve of the rib-to-rib connection of U-ribs, and the state transition probability matrix of the strength evolution of the vulnerable portion of the connection was constructed according to the Palmgren-Miner linear fatigue cumulative damage theory. Finally, the probability distribution vector of the initial state and the state transition probability matrix were used to obtain the residual strength values at different service time of the bridge, and the strength degradation trajectory of the connection of U-ribs was fitted. The results show that the established fatigue state analysis model can consider the correlation of different states during the process of component strength degradation, and can predict the variation of the U-rib fatigue state of the orthotropic plate during the service time of the bridge according to the change of traffic flow-Hence, the service performance assessment of orthotropic plates of steel box girder can be realized and completed.
郭健 杭达. 基于马尔可夫链的钢箱梁正交异性板疲劳状态分析[J]. 土木工程学报, 2020, 53(3): 60-66.
Guo Jian Hang Da. Fatigue state analysis of orthotropic plates of steel box girder based on Markov chain. 土木工程学报, 2020, 53(3): 60-66.
