Why is the "life" of expansion joints two or three years?

Bridge expansion joint refers to the telescopic device set between the two beam ends, between the beam end and the abutment, or at the hinged position of the bridge in order to meet the requirements of bridge deck deformation.Telescopic deviceOn the one hand, it protects the main structure of the bridge from damage, and on the other hand, it ensures the safety and comfort of the vehicle.

The destruction of the bridge telescopic device not only causes the bridge to jump when encountering seams, greatly reducing the driving comfort, but also leads to the destruction of bearings and beams, and the structural durability is reduced.

The telescopic device directly bears the repeated impact of wheel load and the deformation of the bridge structure, and the use environment is relatively harsh, which is the most vulnerable part of the bridge structure to be damaged and difficult to repair. According to our country's relevant standards and regulations in the field of engineering construction and highways, the design service life of the middle bridge is 50 years, the design service life of bridges and above is 100 years, and the design service life of high-grade asphalt pavement is more than 15 years. As an important protection device for the main structure, how long should the bridge telescopic device be? Yes and MissPavement structureConsistent, or as oneLow-value consumablesWhat about replacing it once every two or three years?

Some experts believe that the important role of the bridge telescopic device is to protect the main structure from being damaged, and its design service life should not be lower than the design service life of the pavement structure, and early maintenance and early replacement should be avoided. However, the reporter visited and investigated a number of highwaysConstruction unit, construction units, and even maintenance enterprises, generally believe that bridge telescopic devices belong to wearing parts and consumables in the bridge structure, and the service life is about three years, which is normal.

It can be seen that at present, in the field of highway and bridge construction and maintenance management, the views of experts and scholars are in the minority. The view that bridge telescopic devices are low-value consumables has become a common and even solidified ideology.

What is even more shocking is that after the two-year defect liability period of highway bridges, bridge telescopic devices often begin to have concentrated problems, ranging from concrete structure damage, aging and damage to the waterstop of telescopic devices, and partial fracture and damage of section steel; What is more serious is the destruction and deformation of the overall structure.Comb toothboardThe bolts are loose and fall off as a whole, which endangers the main structure of the bridge and the safety of the vehicle.

The bridge telescopic device is easily damaged, has a short service life, and is frequently replaced, and the main reasons for this are the following aspects.

First of all, there are defects in the structural design of the expansion joint device itself, which is inherently insufficient.

In our country's bridge construction and design, the idea of attaching importance to the overall structure design of bridges and despising the design of bridge accessories exists. Since the introduction of German Mauler expansion joints and Japanese comb plate expansion joints in the 90s of the last century, the bridge telescopic device has not been improved much, and it is difficult to adapt to the reality of many heavy vehicles on our country's highways. Especially in terms of telescopic device design, highway bridge design units, telescopic device R&D and production enterprises lack the whole life cycle of the projectDesign conceptTo a certain extent, there is a lack in overall consideration of project construction, operation and maintenance;

The second is engineeringGeneral contractingUnder the system, some bidding units ignore the quality requirements in the bidding process, and only talk about price, resulting in the winning bid price being lower than or even much lower than the cost price.

These enterprises that win the bid at a lower than cost price can only be in raw material procurement, manufacturing, etc. in order to obtain profitsReduce costs, to make up for losses at the expense of product quality, resulting in the phenomenon of "bad money driving out good money".

For example, the estimated budget of the 80 bridge telescopic device was originally about 3,000 yuan/linear meter, but in reality it is very different, some even as low as less than 1,000 yuan, resulting in the material of the main components of the telescopic device not up to standard, and the phenomenon of shoddy charging is more common;

The third is that the installation quality of bridge telescopic devices is not strictly controlled.

In particular, the installation time of bridge telescopic devices is usually on the bridgeConstruction of the main structureCompletion, near the end of the delivery and acceptance, the compression of the construction period and the rush of the work, etc., make it difficult to ensure the installation quality, especially the concrete structure maintenance is not in place, the delivery and acceptance seem to be glamorous, once the delivery is open to traffic, the problem will be exposed;

The fourth reason has a lot to do with the serious overload of highway vehicles.

When a heavy vehicle is driving at high speed, the damage to the bridge deck telescopic device is particularly seriousVehicle loadThe impact force of the vehicle and the vibration of the beam plate caused by the repeated action are very serious, which accelerates the further damage of the joint.

In addition, water seepage of the bridge deck is also a major cause of bridge joint and component failure.

Especially in the northern region, the water after the melting of ice and snow on the bridge deck due to the use of snow removal agent is corrosive, and the bridge telescopic device generally adopts a single-layer waterstop, the waterstop is damaged, the maintenance and replacement are not timely, and the bridge deck water seeps in through the joints, which in turn causes the corrosion and damage of the steel section, bearing and pier cap of the telescopic device.

The short service life of bridge telescopic devices includes many reasons, and it is even more difficult to escape the fault of the quality of the manufacturer. Enterprises can compete on the same stage by cutting corners and counterfeiting imitations, and even compete successfully. In the field of engineering, some people jokingly call this phenomenon "starving colleagues, exhausting themselves, and pitting owners". Not only does it seriously disrupt the market operation order, but it is also a blow to the entire manufacturing industry.

What makes the industry feel comforted is that the central government vigorously advocatesQuality power, transportation power, vigorously promotedCraftsman spirit。 Relying on cutting corners or even counterfeiting to make profits, the space is becoming increasingly cramped.

Quality is the foundation of the enterprise, the same is true for the bridge telescopic device industry, the competition will be more fierce, the requirements for quality and brand will be higher, only adhere to innovation as the core, quality-oriented, and raise the quality problem to the level of values and modern corporate philosophy to understand, in order to establish an advantage in the competition.