A Study on the Strength and Fatigue Properties of Seven-Wire Strands in Hangers under Lateral Bending

Abstract

Hangers are important tensile members in half-through arch bridges and through arch bridges (HTABs and TABs). The floating deck structures of HTABs and TABs will commonly produce longitudinal deformation and rotate under the effect of temperature and the temperature gradient, which will cause bending deformation at anchorages of fixed-end hangers. This bending deformation can generate adverse bending stress for hangers and decrease the strength and fatigue properties of the seven-wire strands in the hangers. Firstly, theoretical derivation and finite element analysis are conducted to study the bending stress of hangers that is caused by bending deformation. We find that bending stress of hangers is mainly generated by lateral bending caused by the difference in longitudinal displacement at both ends of the hangers under the effect of temperature. Subsequently, the ultimate tensile strength of the seven-wire strands under lateral bending is obtained by FEM and an experimental study. The ultimate tensile strength of the seven-wire strands could decrease by 23.3% when lateral bending is considered. Moreover, the relationship between the fatigue properties of the seven-wire strands and lateral bending is obtained based on observing the ultimate tensile strength under lateral bending. Lateral bending significantly influences the fatigue properties of the seven-wire strands. When the lateral bending angle reaches about 50 mrad, the fatigue resistance of the seven-wire strands drop by almost 40%. The considerable decrease in the strength and fatigue properties of the seven-wire strands indicates that lateral bending has a significant adverse influence on hangers that consist of seven-wire strands. Finally, it is advised to use the tied arch structure for HTABs and TABs to mitigate the adverse influence of lateral bending on hangers.