Bridge Strengthening and Transformation

It is necessary to study, test and popularize the structural strengthening and repairing of old and dangerous bridges and how to improve their bearing capacity of the old bridges.

The significance of bridge structural strengthening

It is necessary to study, test and popularize the reinforcement and repairing of old and dangerous bridges and how to improve their bearing capacity. A lot of information shows that in some countries with developed traffic, the emphasis of bridge construction has been put on the reinforcement and reconstruction of the old bridge, and the new bridge has been reduced to a secondary position. The experience of strengthening or reconstructing old bridges in China also shows that, in general, the cost of strengthening the bridge is about 10%--20% of the cost of the new bridge, and the cost of strengthening and reforming the double curved arch bridge is about 20% ~ 40% of the cost of the new bridge.Therefore, it is not only better and timely to serve the modern transportation and transportation, but also bring great economic and social benefits to the country.

The reasons for the reinforcement of the beam

1) the original design standards of old bridges are low, which can not meet the current requirements of vehicle development. With the continuous development of bridge design specifications, the design load of highway bridges has been developed from steam 6, steam 8, steam 13 to grade 15, steam and 20 and steam - Super 20, and still continues to increase. According to the investigation and analysis, in the national highway, provincial road and county highway permanent large and medium bridge, the design load is only 6.53% of the total and medium size of the large and medium size bridges. The bridge is 9.17%, and the bridge of the remaining 84.3% of the bridge is basically steam. A grade 13 and steam grade 15 load standard.

2) due to defects in design and construction and various adverse effects (such as carbonization, chloride ion invasion, acid erosion, alkali aggregate reaction, freezing thawing, salt damage, etc.), the corrosion of concrete and reinforcement of bridge structure is serious.

3) the bridge has a long service life and is close to its service life. Most of the bridges built in China from 1960s to 70s are still in service. Because of their disrepair and loss of maintenance, it is not suitable for the need of increasing traffic.

4) the influence of unfavorable external loads makes the safety of bridge structure decrease. In China, the biggest cause of this situation is that most of the trucks running on the road are overloaded and overrun, resulting in more than 20% of the bridges.

5) because of the problems of investigation, design and construction, the new bridge can not meet the requirements of use and the use function of the new bridge. It is also an important reason for the bridge to be strengthened.

Bridge Strengthening and Transformation