Lavr Proskuryakov

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Lavr Dmitrievich Proskuryakov

Lavr Dmitrievich Proskuryakov (18 August 1858 – 14 September 1926) was one of the foremost authorities on bridge engineering and structural mechanics in the Russian empire and the early Soviet Union.

Life and career[edit]

Lavr Proskuryakov was born on August 18, 1858, into a large peasant family. In 1884, he graduated from the Saint-Petersburg Institute of Railway Engineers and worked as a designer of bridges. Since 1887, he lectured at the same institute, and starting from 1896, Proskuryakov held the position of full professor at Moscow State University of Railway Engineering.

Even the early Proskuryakov's projects for the bridges across the rivers Western Bug (1885) and Sula in the Ukraine (1887) attract attention by their novelty and ingenuity. The drawings of those bridges were published by Professor L.F. Nikolai, the head of the bridge faculty at the Petersburg Institute of Railway Engineers, in his tutorial on bridge design for railway engineers.[1]

In the summer of 1895, Proskuryakov was sent abroad, according to a decision of the Institute academic council, so as to take part in the International Railway Congress in London, as well as explore local mechanical laboratories and bridges. Besides London, he visited laboratories in Paris, Zurich, Munich, Vienna and Berlin, and then went to the United States in order to get acquainted with the biggest bridge structures and local mechanical laboratories.[2]

Proskuryakov was the first in Europe who rejected the then existing lattice bridge trusses with lots of vertical and diagonal members, which were extremely complicated for design calculations. Instead, he designed a statically determinate triangular web truss with the minimum number of diagonals, so as to ensure the exact stress distributions on a bridge structure under a moving load.

All research and practical activities of Lavr Proskuryakov were aimed at the creation of a perfect bridge structure. And he managed to achieve his goal: this was the mighty 1,000 metres (3,300 ft) long steel bridge across the Yenisei near Krasnoyarsk built during 1896-1899. The steelwork of the bridge consisted of six spans, each 144.7 metres (475 ft) long and 21.64 metres (71.0 ft) height, amounting to 900 tons.[3]

Thanks to its engineering and technical characteristics, the bridge was recognized as the longest in Russia and the second largest in Europe (the first one was in the Netherlands across the Lek River near Kuilenburg). Represented at the Exposition Universelle (1900), the Yenisei bridge's model won a gold medal. The bridge was subsequently approved by the UNESCO for inclusion in the World Heritage List.

Rail bridge over the Yenisei near Krasnoyarsk

When designing the Yenisei bridge's superstructure, Proskuryakov introduced a completely new design — the original trusses with subdivided panels and upward-angled upper chords (Schwedler truss). The engineer has also extended the theory of influence lines for the analysis of the bridge's trusses that allowed to accurately calculate the internal forces in every member in a truss resulting from a moving load. Since then, the theory of influence lines for the analysis of trusses has been used in structural designs both in Russia and abroad. Incidentally, the Yenisei bridge was the first in Russia, during the construction of which they applied the incremental launching method.

Essentially, the Yenisei bridge opened up a new era of Russian bridge engineering. Proskuryakov's statically determinate trusses with subdivided panels and upward-angled upper chords were subsequently widely used by many other bridge engineers. In particular, such a system of superstructures (with a few changeups) was borrowed by Professor Nikolai Belelyubsky in the design of the rail bridge across the Volga River near Sviyazhsk.

Summarizing the practical results of Proskuryakov’s activities in the period from 1892 to 1897, it becomes clear that he managed to elaborate the most suitable types of spans for a variety of bridges. Proskuryakov designed many unique multi-span bridges, including the bridges over Oka near Kashira (1897), Belev (1897) and Murom (1912), Vyatka on the Cherepovets-Vologda-Vyatka line (1902), Volkhov (1902), Amur near Khabarovsk (1916) on the Trans-Siberian Railway, and so forth. Yevhen Paton compared Proskuryakov's bridges to Pushkin's poems.

In 1903, at the discretion of the Society of the Moscow-Kazan Railway, L.D. Proskuryakov was among other bridge-design professionals, both domestic and foreign, who made a rough sketch for the bridge across the Volga River near Kazan with the largest span of 165 metres (541 ft) long, similar to the Yenisei bridge.

In 1904, for the Moscow Circular Railway, he designed two arched steel double track rail bridges — Andreyevsky and Krasnoluzhsky across the Moscow River. Both twin bridges were located within the city, and their graceful appearance fully satisfied the demands, which were imposed to the urban constructions of the day. It is worth noting that it were the Russia's first steel railroad bridges, which had crescent arch spans.[4]

The old railway bridge across the Amur near Khabarovsk

One more important achievement in bridge engineering of Imperial Russia was the famous Amur River Bridge near Khabarovsk, designed by Professor Lavr Proskuryakov. The bridge was constructed as a 2,590 metres (8,500 ft) long steel bridge, carrying one rail track. Opened for traffic on October 5, 1916, the bridge marked the completion of Trans-Siberian Railroad.[5] The height of the bridge from the upper deck to the maximum water surface elevation reached 12 metres (39 ft). It allowed larger ships to pass underneath the bridge even at the highest summer water level in the Amur. The bridge cost the Russian treasury more than 13 million roubles — a colossal sum of money for those times.[6]

Proskuryakov was a strong proponent of the graphical method (or the dummy load method) for the analysis of trusses, which is based on the theory of influence lines. In the period 1891-1892, Proskuryakov held the elective course "The application of graphical statics in civil engineering practice". It is particularly remarkable that two years later, the course became a core and mandatory subject in the railway engineers training programme.

In 1896, when designing the bridge across the Kotorosl River, Proskuryakov for the first time worked out special tables to calculate the bearing strength or load-carrying capacity of a bridge due to the passage of a train. Both the theory of influence lines and tables would greatly facilitate the procedures for truss analysis, so they have ingrained in the practice of bridge engineering around the world.

A prominent educator and mentor of youth, L.D. Proskuryakov trained many talented scientists and engineers. His colleagues and apprentices, such as E.O.Paton, M.M.Filonenko-Borodich, I.P.Prokofiev, P.A.Velikhov, P.Y.Kamentsev, and others, became nationally famous scientists in later times. The teaching methods of engineering mechanics developed by Professor Proskuryakov are now widely used in higher education.

In 1902, Proskuryakov published the first volume of structural mechanics entitled "Strength of Materials". Later, in 1907 he published the second volume — "Structural Statics", as well as the study "On the analysis of continuous trusses". Those works have been included into the golden fund of science. His two-volume handbook went through six editions during his lifetime. The seventh edition was published posthumously, and has become a textbook for all technical institutes of the country.

See also[edit]

References[edit]

Notes[edit]

External links and references[edit]