Fatigue durability study of high density polyethylene stay cable sheathing

Stay cable is the primary load-bearing structure of cable-stayed bridges, and the durability of high-density polyethylene (HDPE) stay cable sheathing is essential to the serviceability, safety, and durability of the entire bridge. Considering the damage owing to fatigue cracks in the HDPE sheathing during actual operation, this paper investigates the strain level on the HDPE cable sheathing under variable loads through on-site experiments on a cable-stayed bridge in service. The fundamental fatigue load characteristics were analyzed. The cable fatigue lifetime was further studied to reveal the major factors affecting the distribution pattern of the lifetime of the HDPE sheathing. The study results partially explained the cause of early fatigue failure in certain cable sheathing and provided theoretical proof for engineering measures for increasing the lifetime of HDPE sheathing.