Reinforced Composite Box Girder Bridge

1、 Overview of Bridges

Xiuzhen River Bridge

The upper structure of the Xiuzhihe Bridge is a prefabricated partially PC continuous box girder, and the lower structure is a pile column pier. The design load of the bridge is steam exceeding 20; Hanging -120; The bridge is arranged in sections, with a deck layout of 0.5m (outer guardrail)+12m (carriageway)+1m (inner guardrail)+1m (central divider)+1m (inner guardrail)+12m (carriageway)+0.5m (outer guardrail); The full width of the bridge is 28.0m.

2、 Bridge disease detection

During regular inspections, it was found that 98 new vertical cracks were added to the web of the composite box girder of the entire bridge, with a joint length increase of 72.35m and a joint width of<0.15mm. A U-crack is added at the mid span position of the web plate of the left 32 # hole 1 # box girder, with a length of about 2.8m, a width of 0.12mm for the web plate joint, and 0.06mm for the bottom plate joint. Two horizontal cracks have been added to the web of the box girder, with a total length of approximately 4.8m and joint widths of 0.08mm. There are 7 new transverse cracks added to the bottom plate of the box girder, with a joint length of 5.85m and a joint width of ≤ 0.08mm. Three longitudinal cracks have been added to the bottom plate, with a joint length increase of 31.5m and a joint width of 0.10mm. There are 28 new vertical cracks added to the pier top diaphragm beam, with a length of 25.8m and a width of<0.15mm.

3、 Selection of reinforcement plan

The overloading and long-term rolling of highway vehicles have resulted in insufficient bearing capacity of the box girder, which is an important reason for the occurrence of cracks in the bridge. Therefore, in response to the insufficient flexural bearing capacity of the box girder span under actual operating loads, the Horse prestressed carbon fiber plate reinforcement system is adopted to improve the stress state of the original structure, seal small cracks, and improve the bearing capacity and durability of the bridge.