The paper examines the damage tolerance of prestressing steel wire-strands failed after being exposed without protection to environmental action for 30 years as tie-down cables of a cable-stayed bridge. The influence of corrosion pitting, cross-section losses and possible assisted cracking on the tensile behavior of the Zn-coated prestressing steel strand-wires was experimentally determined, as well as their susceptibility to aggressive environments. A damage tolerance assessment was completed by performing fracture tests of as-received wire-samples exposed to an aqueous solution of ammonium thiocyanate while tensile loaded by applying a constant load followed by an increasing load at low strain rate. The fractographic analysis of the wires broken in-service and in-laboratory proved the induced damage to be very similar and provided evidence of environmental damage in some of the service ruptures. The damage tolerance assessment is in agreement with the two types of wire ruptures found in the failed wire-strands. These sequentially occurred over the 30 years of service, with the brittle ruptures of the mostly exposed peripheral wires being due to environmentally assisted cracking and preceding the ductile ones of the remaining wires by mechanical overloading.

本文研究了预应力钢绞线作为斜拉桥的束缚电缆暴露在无保护状态下长达30年后的破坏耐受力。实验确定了腐蚀点蚀，横截面损失和可能的辅助开裂对镀锌预应力钢绞线的拉伸性能的影响及其对侵蚀性环境的敏感性。通过对暴露在硫氰酸铵水溶液中的原样钢丝样品进行断裂试验来完成破坏耐受性评估，同时通过施加恒定载荷然后在低应变速率下增加载荷来承受拉伸载荷。对在役和实验室中折断的金属丝的分形分析表明，诱发的损伤非常相似，并为某些断裂中的环境破坏提供了证据。损伤容限评估与在失效的钢绞线中发现的两种类型的钢丝断裂一致。这些顺序是在使用30年后发生的，大部分暴露在外的钢丝的脆性断裂是由于环境辅助的开裂所致，并且由于机械过载而使其余的钢丝中的易延展的钢丝断裂。