锈蚀高强钢丝及拉索承载性能退化的概率评估

Cable supported bridges are widely built in recent three decades. As time passing by, the load carrying capacity of cables are deteriorated due to high strength steel wire corrosion. Some stay cables and hangers are even broken without any warning due to poor maintenance and residue strength assessment of corroded cable becomes a pressing and challenging task. This project will get the corroded high strength wire from bridge site and by accelerated corrosion of HDPE sheath coated high strength steel wire firstly. The statistical analysis of corrosion surface pits and uniform corrosion of corroded wire will then carried out to get the parameters of distribution models, the relationship between corrosion parameters of different located wires can also be derived. Numerical simulation will be carried out to identify and quantify the effects of pitting corrosion on strength degradation of corroded wires. Static tension loading and fatigue loading test on corroded wires will further carried out to derive degradation parameters of probabilistic distribution functions for stress-strain relation and fatigue life. Based on the derived probabilistic distribution model for the corroded wire, stochastic strength and fatigue life of corroded cable will be further assessed by Monter Carlo method. The degradation characteristic of load carrying capability of corroded cable will be analyzed. The semi analytical and semi numerical probabilistic distribution model for strength and fatigue life of corroded cable will be further deducted and updated by the Monter Carlo simulation result. Static loading test and fatigue test of small scale corroded cable model will also be conducted to verify the analytical and simulation results. This work can reveal degradation mechanism and evolution of loading capability of corroded cable. It will be the foundation work of stochastic strength and fatigue life evaluation of corroded cable, and it has wide application perspective in the future.

本项目将结合实桥锈蚀拉索取样和实验室加速腐蚀模型拉索、高强钢丝腐蚀形貌观测统计、锈蚀高强钢丝及小尺寸拉索模型加载实验、有限元和蒙特卡罗法模拟分析，及概率理论研究锈蚀拉索的承载性能退化规律。首先通过实验室加速腐蚀HDPE护套包裹高强钢丝拉索模型，结合实桥锈蚀拉索样本，观测统计锈蚀钢丝的均匀锈蚀和坑蚀分布特征参数及位置相关性。进一步通过锈蚀钢丝的有限元模拟和加载实验，确定锈蚀高强钢丝的应力-应变本构关系参数和疲劳寿命参数退化的概率分布函数及其与腐蚀形貌参数的相关性。采用蒙特卡罗法模拟加载并统计分析锈蚀拉索承载性能退化特点，并推导半解析半数值的锈蚀拉索静力承载性能和疲劳寿命的概率分布函数并以蒙特卡洛方法模拟结果予以修正。再进一步采用锈蚀小尺寸拉索模型加载实验结果验证，最终揭示锈蚀拉索承载性能退化机理和演变规律。本项目研究成果为锈蚀拉索承载性能的概率评估方法提供理论依据，具有广阔的应用前景。

本项目将结合实桥锈蚀拉索取样和实验室加速腐蚀模型拉索、高强钢丝腐蚀形貌观测统计、锈蚀高强钢丝及小尺寸拉索模型加载实验、有限元和蒙特卡罗法模拟分析，及概率理论研究锈蚀拉索的承载性能退化规律。首先通过实验室加速腐蚀HDPE护套包裹高强钢丝拉索模型，结合实桥锈蚀拉索样本，观测统计锈蚀钢丝的均匀锈蚀和坑蚀分布特征参数及位置相关性。进一步通过锈蚀钢丝的有限元模拟和加载实验，确定锈蚀高强钢丝的应力-应变本构关系参数和疲劳寿命参数退化的概率分布函数及其与腐蚀形貌参数的相关性。采用蒙特卡罗法模拟加载并统计分析锈蚀拉索承载性能退化特点，并推导半解析半数值的锈蚀拉索静力承载性能和疲劳寿命的概率分布函数并以蒙特卡洛方法模拟结果予以修正。再进一步采用锈蚀小尺寸拉索模型加载实验结果验证，最终揭示锈蚀拉索承载性能退化机理和演变规律。本项目研究成果为锈蚀拉索承载性能的概率评估方法提供理论依据，具有广阔的应用前景。