# Dynamic Load Test and Contact Force Analysis of the AERORail Structure
## 1 Introduction  
The AERORail Transportation System referred to as AERORail, is a new type of transportation system in the form of a cable-supported rail combined structure (see Figure 1) composed of multispan continuous string cables, rails, lower supports and related power supply and control systems [1]. Similar to existing top-supported suspension bridges or stress zone bridges, the typical projects include the Rio-Colorado Suspension Bridge in Costa Rica (108 m in span), the Bad Sand Bridge on the Elbe River in Germany (100 m in span), Su Rifeng Bridge (48 m in span) in central Kyushu, Japan and Taojin Bridge (74 m in span) in Taojin Village, Dongkou County, Hunan, China [2,3]. The AERORail structure uses steel as the structural material, replacing the use of concrete and prestressed concrete in the superstructure; it cancels the heavy superstructure in traditional bridges and forms a common stress system directly formed by the rail and the string cable, which is a veritable hollow structure in the sky; its structural rigidity mainly comes from the stress rigidity generated by the prestressing of the string cable [4]. Due to its obvious structural flexibility characteristics, its structural dynamic characteristics are the focus of research and important structural characteristics that must be mastered in the future application process. The problem corresponding to the characteristics of its flexible structure is that when it is subjected to moving loads, the force and deformation, and vibration and stability of the structure have obvious coupling effects between the structure and the moving loads. As a flexible structure, its structural form is somewhat similar to that of string beams. The biggest difference from conventional string beams used in buildings is that AERORail is simpler in structure, and the overall structural size is more represented as a longitudinal one-dimensional structure, even in the lateral direction, showing that the lateral dimension is much larger than the height dimension [5]. Second, the servicing load on the AERORail is a moving load, and the load causes the structure to deform considerably when it is no-load and full-load [6]. Therefore, from the stress point of view, the AERORail structure is more like a stress ribbon structure. For such light and flexible structures with pretensioned cables, [PERSON] [7] studied the prestressing process, and most typical experimental studies are represented, including both full-scale tests and downscale orthogonal tests. The static behavior and the effect of a prestressed cable on structural stability are presented, followed by a typical full-scale static loading test with dynamic behavior, such as the natural vibration characteristics. Based on the structural characteristics of a tensioned string bridge, [PERSON] [8] used the Rayleigh method to derive formulas for calculating the frequencies of vertical, antisymmetric and lateral bending vibrations. [PERSON] and [PERSON] [9] derived the kinematics and governing equations of motion of a general flexible multibody system and their extension to moving loads and presented a method to handle discontinuities when moving loads separate from the flexible structure. [PERSON] [8] studied the dynamic structural characteristics of a tensioned string bridge based on the Rayleigh method to derive formulas for calculating the frequencies of vertical, antisymmetric and lateral bending vibrations. He found that the shape and physical characteristics of the main cable have a greater impact on the vertical symmetrical vibration frequency than the lateral bending frequency, and the vertical bending symmetrical vibration frequency increases with an increasing rise-to-span ratio. The tension force of the main cable has no influence on the frequency of tensioned string bridges. The first-order frequency of the tensioned string bridge is generally the vertical bending symmetrical vibration frequency. The fundamental frequency of a structure can be greatly increased, thereby increasing the overall rigidity of the structure.