The viaduct body is so large, why is the contact area with the bridge piers so small? Is this safe?

The bridge body of the viaduct is only more than ten meters wide and weighs about dozens of tons. However, the contact area between such a heavy and large viaduct and the piers is very small. The bridge piers are well repaired, why do we need to add a few supports in the middle? Generally speaking, the bridge structure can be roughly divided from top to bottom into bridge deck paving, bridge deck, volumetric fabrication, bridge pier cap foundation, etc. Among them, the connections between the bridge deck and the bridge piers are not all rigidly fixed. Most of them allow a certain degree of displacement. The main reason is to cope with the deformation of the bridge body and ensure the service life and structural safety of the bridge. .

Take the plate rubber bearing as an example. It is composed of multiple layers of natural rubber and at least two layers of thin steel plates. It has sufficient numerical stiffness and elastic deformation, and can well withstand vertical loads and Adapt to the rotation of the beam end. During installation, first set the battery-bearing support plate on the pier. Then, after determining the center line, put on the rubber to make a smooth layer of polytetrafluoroethylene material, and finally attach the upper support plate. When the bridge deck moves horizontally or left and right, the stability of the bridge body can be ensured by sliding with the superstructure.

So if a product with such excellent performance is damaged, how should it be replaced? Commonly used methods include the jacking method, that is, using a hydraulic jack to jack up the beam simultaneously, and then remove the original old supports. Then clean the top surface of the FM battery and the bottom surface of the box beam, place the new supports, and fix the bolts. , the jack can be removed after it is lowered into place. Although compared with the design of continuous bridge piers and bridge bodies, subsequent maintenance and replacement are required, but the service life of the bridge cannot be underestimated.

Finally, in the connection method between the bridge pier and the bridge body, there is also a single-column pier or single-column pier, which can support the entire bridge deck with only one fulcrum in the middle of the bridge, and its left and right suspended The design looks very dangerous, so will it roll over easily? In the early days, due to the small area and low cost of single-column piers, during the actual construction process, as long as the conditions were suitable, more single-column piers were chosen. However, as the number of rollover and overturning accidents gradually increased, its shortcomings were gradually exposed.

On December 18, 2021, a bridge rollover accident occurred on the Huyu Expressway section in Ezhou City, Hubei Province. The entire bridge section of the accident tilted to one side, and the long bottom of the accident vehicle was the key to the frivolity. According to the investigation, the truck carried 198 tons and was overloaded by 400 tons. Although it is obvious that overloading was the main cause of this accident, the natural disadvantage of poor lateral stability of single-column pier bridges cannot be ignored.