## 1 Introduction  
Pipeline bridges carry pipelines of natural gas, oil, or water across rivers, canyons, or other natural or man-made obstacles. Pipeline bridges are mainly designed as suspension bridges for cases with main span lengths over 200 m. Compared with highway suspension bridges, pipeline suspension bridges are much narrower, blunter, lighter, and more flexible, and thus, they are highly sensitive to wind action. As a result, wind loads should be carefully addressed to ensure the safety of a pipeline suspension bridge. If the pipeline is damaged by strong winds, the oil or gas will leak out, which can even result in catastrophic fire or explosion disasters. This would not only cause significant economic losses but also lead to heavy casualties and significant secondary environmental pollution. A natural gas pipeline exploded in the southeast of New Mexico in August 2000. Twelve people were killed, and two nearby pipelines bridges were severely damaged in the accident [1]. In November 2013, an oil pipeline exploded in Qingdao, China, and the blast killed 62 people [2]. In the forthcoming two decades, the construction of pipeline networks will be promoted in Southwest China (e.g., Yunnan and Guizhou province). Unfortunately, glaze ice accretion may occur in these regions, for example, the freezing rain and snowstorm event at the beginning of 2008 in southern China. As a result, pipeline suspension bridges will confront the issue of ice accretion. Until now, a large number of investigations have shown that glaze ice accretion can modify the aerodynamic force coefficients of a circular cylinder (which may represents a transmission line, a bridge hanger, or a stay cable) and induce galloping due to the change of the aerodynamic shape, and ice accretion may also lead to structural failures due to the self-weight of the ice [3, 4, 5, 6, 7, 8, 9, 10]. The cross sections of pipeline suspension bridges (including the truss stiffening girder, pipeline, grate plate, and guardrail) are much more complicated than circular cylinders. The findings of previous studies cannot be directly used to design and maintain pipeline suspension bridges. Therefore, it is necessary to evaluate the effects of ice accretion on the aerodynamic properties of pipeline suspension bridges. Investigation of ice accretion is the first step toward studying its effect on the aerodynamic response of a structure [11, 12]. Recently, some studies focused on the glaze ice accretion on circular cylinders [7, 13, 14, 15, 16, 17, 18], insulators [19, 20], airfoils [21, 22], and wind turbine blades [23, 24]. The accreted ice mass and the detailed shapes were studied. The radial ice accretion on circular cylinder was most widely studied in the literatures, and ice accretion model of a circular cylinder can be simulated as follows: (1) the simplified ice shape, including triangle shape, crescent shape, ellipse shape, D-shape, sector-shape, and so on (as shown in Figure 1, the first four ice shapes are more common in power transmission lines, and the latter three ice shapes are more common in stay cables), was covered on the circular cylinder, which was extracted based on icing tests or field observations [4, 9, 14, 18, 25, 26, 27, 28]; (2) the complicated artificial ice model was obtained by 3D scanning and printing technology [29]; (3) the real ice model was acquired in the icing wind tunnel [5, 7, 15]. The ice shapes on pipeline suspension girders may be very different from those in the abovementioned objects. In addition, some experimental results demonstrated that the ice shape is dependent on the cylinder diameter \(D\). [PERSON] [30] showed that the uniform radial ice thickness of the circular cylinder is related to its diameter based on a precipitation model, and ice shape depends on the diameter of the wire. [PERSON] et al. [14] experimentally investigated the ice accretion on circular cylinders (\(D\) = 38.1 and 89 mm) and showed that the thermodynamic solidification processes and ice surface characteristics are related to the diameter.