Effect of Ice Accretion on the Aerodynamic Responses of a Pipeline Suspension Bridge

Abstract

Ice accretion is a major concern that may endanger the operation safety of structures and even cause serious casualties in cold regions. Under freezing rain conditions, the size and shape of the accreted ice on different diameter circular cylinders are investigated in a refrigerated precipitation icing laboratory. The ice size and shape are closely related to cylinder diameter and accretion duration. The engineering geometrical models of the ice accretion on circular cylinders are extracted. The aerodynamic displacement responses of a 1:25 aeroelastic model of a pipeline suspension bridge with and without ice accretions are experimentally recorded using Micro-Epsilon sensors. Analytical expressions to calculate the vertical and lateral displacements are derived, and the differences between the conventional method and the newly derived one are further analyzed to manifest the theoretical significance. For three-degrees-of-freedom motions, the vertical and lateral displacements cannot be separately determined by the signals of vertical and lateral sensors, respectively. Some strategies are recommended to reduce the errors induced by using the conventional formulations. The influences of initial angle of attack, ice shape, pipeline diameter, and turbulence intensity on girder displacement and wind cable tensile force are comprehensively investigated. The aerostatic responses are greatly influenced by the aforementioned parameters. The aerodynamic analyses reveal that the ice accretion can obviously increase wind-induced responses, that is, deteriorate the wind-resistant performance, which should be taken into careful consideration. The present work can provide beneficial references for the wind-resistant design of similar type of bridges, especially under pipeline ice accretion conditions.