## 2 Design Concepts and Features
### Innovative Design Concepts  
The Jinghe Bridge is designed with the basic principles of regional, cultural and integrated characteristics and with the design concept of \"showing the humanistic characteristics of the region and depicting a beautiful picture of the future of the region\". The starting point for the bridge landscape design is \"harmonization with the hub and the surrounding environment\". Since both banks of the bridge are steep slopes, the river is relatively narrow and the design elevation of the bridge deck is relatively higher. Therefore, in order to avoid the bridge form tending to be conventional, to better coordinate the height of the mountains on both sides of the river, and to echo the plane curve of the hyperbolic arch dam, so that the bridge form and the environment can achieve coordination and balance in the configuration, a pioneering innovation was made to the main arch rib. The traditional single main arch rib design is abandoned, and the structural characteristics of butterfly arch bridge and medium-bearing arch bridge are mixed, adopting the medium-bearing space Y-shaped combined steel box arch. The arch ring and arch seats are divided into a single arch segment and a double arch segment, the arch ring is Y-shaped in space, and the arch ribs are separated into two pieces along the bridge, from single to double, from simple to complex, and from complex to simple, combining complexity and simplicity, which not only enables the shape of the arch to be more in the contemporary sense and three-dimensional sense of space, but also solves the traffic organization problem of T-shaped intersection. The main and secondary arch collaboration Y-shaped arch bridge is an innovative arch bridge type, and the construction of this unique shaped arch bridge is the first of its kind in China. The imagery of the Y-shaped form is \"Jinghe String Moon\". The overall shape of the structure is very dynamic and tense. The rounded three-dimensional arcs on the outside of the arch ribs emphasize the landscape theme of \"Jinghe String Moon\" and convey the spirit of innovation and progress, and the arch rib shape resembling a sail and a rainbow expresses the symbolic meaning of auspiciousness. The main and secondary arch collaboration Y-shaped arch bridge not only has a unique and beautiful shape, excellent landscape effect, favorable traffic visibility, and safe and reliable passage, but also can be applied to various terrain conditions, while reducing the number of arch ribs so that the economic performance is outstanding. In addition, in the new mode of single-double combination, the main and secondary arches are synergistically bearing, which also enables the structure to obtain better mechanical properties, and the triangular structure of the arch ribs from single to double increases the structural stability performance. The main and secondary arch collaborative Y-shape thin-walled steel box arch bridge is mainly composed of main and secondary arch ribs, connecting ribs, suspenders, main girder, etc. The main components of the bridge are shown in Figure 2. The calculated span  
Figure 1: Three-dimensional rendering of main and secondary arch collaborative Y-shaped steel box arch bridge: (**a**) isometric drawing; (**b**) side-view drawing. combination of the bridge is 2 \(\times\) 19.5 m + 197 m (14.5 m + 28 \(\times\) 6 m + 14.5 m) + 2 \(\times\) 19.5 m, the main girder adopts double boxes and is a double-cell \(\pi\)-type steel box girder, the girder length is 274.7 m, the standard section width is 18.0 m, the main girder has a viewing platform at the intersection of double arches and main girder, the main girder width is 36.0 in the widened section and the girder height is 2.0 m [31]. The bridge layout is shown in Figure 3. The main arch adopts no hinge arch, the side and main span of the main girder use suspended continuous girder structure, and vertical bearings are set at the pier and crossbeam of the arch. The suspenders are flexible cables with a spacing of 6 m and a total of 29 pairs.