A few words about the destruction of bridges. Crimean bridge

М.Терлецький
01 вересня 2022 р.

"On Friday noon, July the twentieth, 1714, the finest bridge in all Peru broke and precipitated five travellers into the gulf below."

The citizens of Peru crossed themselves and whispered prayers of thanks for their deliverance. But in the mind of Brother Juniper, a humble monk who witnessed the catastrophe, burned the question, "Why did this happen to those five?"

As Brother Juniper's investigations illuminate the possibility of an Intention to the disaster—involving the lives left behind as well as those lost on the bridge—the reader rediscovers the one "bridge" between the land of the living and the land of the dead that does not fall.

Wilder Thornton. The bridge of San Luis Rey

Mankind has accumulated vast experience in building bridges. It would seem that all the negative points are known, and if they are taken into account in the process of designing the structure, in the subsequent proper conduct of construction work and further operation, the bridge must stand unshakably for the entire period specified by the project. Alas, this does not always happen.

The bridge, like any engineering structure, can collapse.

One of the most well-known causes of the destruction of bridges is resonance, that is, the phenomenon of a sharp increase in the amplitude of oscillations of the bridge structure under periodic external action, when the frequency of the external action coincides with the internal frequency of the structure. The most well-known external influence in this case is the wind.

Nature sometimes creates such external influences in strength and nature that are not typical for the area where the bridge is located and therefore could not be taken into account: floods and sudden surges of water that simply wash away the bridge or destroy its supports and the soil under them, earthquakes, landslides ... Another reason for the destruction of the bridge may be its improper operation, in particular, the excess of static and dynamic loads.

It should be noted that ship accidents in a collision with bridge supports can also have catastrophic consequences for the bridge.

The materials included in the design, in particular metal, can behave specifically not only under mechanical influences, but also under thermal ones. For example, exposure to fire for a time exceeding the fire protection limit of a metal structure is likely to be fatal to it.

Well, a separate type of negative impact on the structure can be a deliberate impact on the bridge by air strikes or shelling during the war with the aim of destroying it. It was during the wars in the history of mankind that the destruction of bridges most often occurred. So the largest number of bridges were destroyed in the 20th century by air strikes or shelling during the Second World War.

Wilder's novel The Bridge of Saint Louis describes the collapse of an Inca-built suspension bridge in Peru on the road between Lima and Cuzco in 1714, at a time when certain providential people were passing over it...

As for the Crimean bridge, referred to as "Construction of a transport crossing across the Kerch Strait", its bridge deck is a rather impressive structure with an orthotropic slab and a reinforced concrete slab 200 mm thick, which, obviously, can be destroyed hit by heavy bombs. Surely, by those that were used during the bombing by Russian aircraft on the Ukrainian city of Mariupol. The only question is to deliver them and drop them on the bridge.

Although the weak point of the bridge is the huge metal arches, the difficulty of destroying them lies in the fact that they need to be hit from a long distance.

However, shelling the carriageway with artillery, even without significant damage to the supporting structures, can significantly reduce the throughput of the bridge.

One way or another, life will show the possibility of this, as well as the correctness of the calculations of the general designer of JSC "Institute Giprostroymost - St. Petersburg", compliance with the standards during construction work by the contractor LLC "Stroygazmontazh", and how His Majesty Nature and the Armed Forces of Ukraine will behave with the bridge .

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