Design of Main Bridge of Fengshi River Bridge

Fengshi River Bridge is a major bridge on Jiyuan-Shaoyuan Expressway and the main bridge of the Bridge is a typical mountainous region high-rise pier,long span and long continuous unit rigid-frame bridge having seven spans of(66+5×120+66) m arranged in one continuous unit.The main girder of the bridge is of the single cell single box section and the main piers are the rectangular hollow thin-wall piers.To accommodate the deformation of the main girder,in the design,the dimensions of the side pier shafts in the longitudinal direction of the bridge were reduced,the girder depth was increased and the law of the girder depth variation was optimized,the vertical prestressing was appropriately increased and the permanent prestressing distribution in the girder was improved to prevent oblique cracks from occurring in the webs of the girder.At the time the prestressing strands were tensioned,both the concrete strength and age were controlled.The preset midspan camber of the girder was also appropriately increased to prevent excessive late period midspan deflection of the main spans and the relatively small side and main spans were chosen to facilitate the construction.