桥梁缆索断面钢丝腐蚀进程差异性试验

Experimental Study on Corrosion Process Differences of Bridge Cable Cross Section

为实现桥梁缆索断面内高强钢丝腐蚀进程差异性量化表征,进而支撑该类构件在服役期内的强度退化模拟与承载力评定等工作,以镀锌钢丝缆索为对象,采用旧索构件破除实测与人工加速腐蚀试验相结合的方法,构造相邻层钢丝腐蚀进程差异性指标,研究了实际服役环境下的平行钢丝缆索断面腐蚀进程差异性。进一步考虑缆索断面构造特征及护套可能出现的病害类型,通过捆绑试件加速腐蚀试验,研究试验环境下平行钢丝缆索断面腐蚀进程差异性,护套破损对断面腐蚀进程差异性的影响以及钢绞线内外丝腐蚀进程差异性。研究结果表明:护套整体老化失效时,平行钢丝缆索断面相邻层钢丝总体腐蚀进程差异系数不拒绝正态分布,均值与变异系数分别为0.675 8、0.254 3;实际服役环境下总体腐蚀进程差异系数均值水平更高、变异性更强,腐蚀介质沉积效应对缆索断面钢丝腐蚀进程差异性的影响因破损形态而异;随着腐蚀时间的延长,断面总体腐蚀进程差异性逐渐减弱,钢绞线内外丝总体腐蚀进程差异系数概率分布特征由对数正态分布向正态分布过渡。

The purpose of thisresearch was to quantitatively characterize the corrosion process differences in the high-strength steel wires of a bridge cable cross section and further support the corresponding strength deterioration simulation and bearing capacity evaluation. The galvanized steel cable was the main focus.A replaced cable specimen was tested, and accelerated corrosion experiments were conducted. The corrosion difference coefficient of wires in adjacent layers was introduced, and the sectional corrosion process differences on parallel wire cables in the actual in-service environment were investigated. In addition, the features of the constructed cable section and the potential causes of sheath deterioration were considered in a series of accelerated corrosion experiments. Subsequently, the sectional corrosion process difference of parallel steel wire cables, the influences of sheath damage on the corrosion process difference, and the corrosion process difference between the inner-side wire and outside wire of the steel strand in an experimental environment were investigated. The results show that the overall corrosion process difference coefficient of the wires in adjacent layers of a parallel wire cable section can be described by a normal distribution when the sheath is integrally aged and fails in protection. The mean value and coefficient of variation are 0.675 8 and 0.254 3, respectively. In the actual in-service environment, the mean value of the overall corrosion process difference coefficient is higher, and the variability is stronger. The influences of the deposition effect of a corrosive medium on the overall corrosion process difference of the cable cross section are different according to the damage shape of sheath. With an increase in the corrosion period, the overall corrosion process difference of the cable cross section tends to weaken, and the probabilistic distribution of the overall corrosion process difference coefficient between the inner and outer wires of the steel strand varies from a lognormal distribution to a normal distribution.