Liuerying (Ma Yi Line) separated overpass is located in the KJ-8 section, the Gao Yu interchange CRK35+571, of the reconstruction and expansion project of Shi 'an, Hebei Province, which design load is: highway - class ⅰ (widened and newly built bridge); Bridge deck width: double width 2× net -17.25m; Design flood frequency: 1/100; Environment category: Class Ⅰ; Peak acceleration coefficient of ground motion: 0.15g (seismic intensity Ⅶ).
The upper part adopts 3×20m prestressed concrete composite box beam; The lower part adopts column pier, column platform and bored pile foundation. The azimuth of the bridge is 83 degrees north by east. The superstructure is composed of 6 main beams, each of which is constructed separately and simply supported in the longitudinal direction first and then continuous. After forming 3-span continuous beams, each box girder is connected through a diaphragm. The main beam concrete design label is C50, and the bridge deck pavement layer is 12cm thick C50 concrete cast-in-place layer + waterproof layer +10cm thick asphalt pavement layer.
The bridge was originally designed as a jointed bridge, and when it was changed to a seamless bridge, due to the tight construction period, the main beam, pier and its foundation, abutment foundation part were kept in the original design, and the main part of the seamless transformation of the abutment was carried out. The abutment of the jointed bridge was changed into an extension of the bridge deck, and the abutment plate was changed into a guide plate and a transition plate.
The construction cost of the seamless transformation of Liuerying separated overpass increased by 79,900 yuan, but the durability of the bridge can be improved after the transformation, and the maintenance and maintenance cost of the expansion joint can be reduced by 4,701,600 yuan. It avoids the repair, maintenance and replacement of expansion joints, improves the capacity of highways, avoids traffic jams, brings convenience to the travel of residents, and indirectly drives the prosperity of the local economy.
Liuerying (Ma Yi Line) separated overpass was constructed by Hebei Expressway Administration (Group), and designed by China Communications First Highway Survey and Design Institute Co., LTD. Hebei Transportation Planning and Design Institute. The College of Civil Engineering of Fuzhou University is responsible for the transverse research project with the bridge as the background. The design of the bridge has been guided and the structure of the bridge has been studied. It was completed and opened to traffic in 2015.
（a）Side view of bridge
（b）Bridge deck photos