Maintenance and reinforcement of Longgang Bridge

Crack repair and bonding carbon fiber

Bridge disease status

(1) There are many transverse cracks in each large hole plate beam. The maximum width of the cracks is 0.21 mm, and the lengths are different. Some of the transverse cracks near the mid-span position are long and extend to the web.

(2) There are longitudinal cracks in part of the large-hole slab bridge span. The maximum crack width is 0.33 mm and the longest is close to 1/2 of the slab length. The beam bottom plate is in a cracking state.

(3) There are obvious transverse cracks near the bottom of the downstream pier of Pier 3, with a width of 0.21 mm, a depth of 7.2 cm, and a length of 2.5 m.

(4) A large transverse crack appeared in the middle of the lower beam of Pier 14 and the crack extended to the bottom of the beam with a width of 2.53mm

5) There is a hollow area of 30 cmXZO cm at 1.4 m of the lower beam of the No. 14 pier, and there are 6 longitudinal cracks on the outer surface, and the maximum width is 0.31 mm.

(6) The outer surface of the bottom of piers 17-19 is severely eroded, the coarse aggregate is exposed to damage, and there are vertical cracks.

(7) The pavement of the entire bridge was severely damaged, many steel meshes were exposed, and some sections of the sidewalk had collapsed due to the existence of uranium, and the expansion joints of the entire bridge were damaged to varying degrees. And the connection between the expansion joint and the pavement concrete of the bridge is not smooth.


Bridge reinforcement plan

Reinforcement design principles

On the basis of fully grasping the external conditions and current situation of the bridge structure and correctly analyzing the causes of the disease, we fully compare and select the existing domestic and foreign repair and reconstruction methods with good treatment effects, economic and reasonable, and convenient construction. At the same time, comprehensive consideration of social and economic benefits.

Based on the above points, this design is based on the design principles of safety, reliability, and economy.

Repair structural defects and restore its integrity

(1) Treat the transverse cracks in each large-hole slab beam, some longitudinal cracks in the large-hole slab beam, the cracks in the pier column and the cracks in the crossbeam of No. 14 pier, according to the width of the cracks to restore the durability of the structure.

Principle of crack treatment: According to the width of the crack, it is treated according to the width. When the crack width is 8 Yan 0.20 mm, it is treated with epoxy mortar; when the crack width o<O.20 mm, it is sealed with epoxy mortar.

(2) Fill the cavities of the beam with epoxy mortar.

Beam reinforcement

Paste carbon fiber cloth on the bottom plate of the large-hole slab beam of the full bridge (Figure 2) to limit the cracks of the beam bottom plate from cracking under the car load, thereby enhancing the flexural rigidity of the beam body

Repair and reinforcement of diseased bridge piers

In view of the obvious lateral crack disease near the bottom of Pier 3, the outer surface of the pier bottom of Pier 17-19 was severely corroded, the coarse aggregate was exposed, and the vertical crack disease was caused. First treat the cracks, and then paste the circular carbon fiber cloth and the vertical carbon fiber cloth on the diseased parts of the pier to limit the continued expansion of the pier cracks, as shown in Figure 3.


In conclusion

(1) In the reinforcement design, external paste reinforcement is adopted for slab beams and bridge piers. The plan is safe, reliable, and economical.

(2) After structural repairs are not foolproof, stricter maintenance and management should be carried out. Anti-collision facilities and more eye-catching anti-collision warning signs should be installed on the main channel piers, and overweight vehicles should be controlled to ensure structural safety.

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