Analysis of the environmental degradation effects on the cables of 'La Arena' bridge (Spain)

摘要

After nearly 25 years of service, some of the wires of the tendons of "La Arena" bridge (Spain) started to exhibit the effects of environmental degradation processes. "La Arena" is cable-stayed bridge with 6 towers and a reference span between towers of about 100 meters. After a maintenance inspection of the bridge, evidences of corrosion were detected in some of the galvanized wires of the cables. A more in-deep analysis of these wires revealed that many of them exhibited loss of section due to the corrosion process. In order to clarify the causes of this degradation event and to suggest some remedial actions, an experimental program was designed. This program consisted of tensile and fatigue tests on some strand samples of the bridge together with a fractographic analysis of the fracture surfaces of the wires, its galvanized layer thickness and some hydrogen measurements (hydrogen embrittlement could be another effect of the environmental degradation process). Once the type and extension of the flaws in the wires was characterized, a structural integrity assessment of the strands was performed with the aim of quantifying the margins until failure and establishing some maintenance recommendations.