KYIV SCHOOL OF THE THEORY OF STRUCTURES

The paper presents a review of more than a century-long history of Kyiv school of the theory of structure, the foundation of which was laid by world-famous scientists V.L. Kirpichov and S.P. Tymoshenko. The birth of the Kyiv scientific school of the Theory of structures is associated in this paper with the establishment at the Kyiv Polytechnic Institute the Strength of Materials Department. It is noted that further formation and development of the theory of structures was facilitated by the creation in 1918 of the Ukrainian Academy of Sciences, the Institute of Mechanics of the NAS of Ukraine, expansion of relevant research in higher education institutions, creation of new academic and sectoral research institutions, most of which is located in Kyiv. The contribution of Kiev scientists to the development of methods for analyzing spatial structures of bar and shell type, their inelastic behavior, as well as dynamics and stability is reflected. Particular attention is paid to the fundamentally new opportunities for the development of the theory of structures in the era of numerical analysis. The successes of Kiev mechanics in the field of development and improvement of structure analysis numerical methods, such as the finite difference method and various modifications of finite element methods, are emphasized. Kiev engineers and scientists are also known for their developments in the field of design and calculation of modern cable-stayed structures, as well as optimal design. The activities of the scientific school of structural mechanics of the Kyiv National University of Construction and Architecture are also covered in the review. In the final part of the paper the new issues connected with the justification of calculation models and the analysis of reliability of constructions are considered. Some of this problems are dictated by the demands of practice, in particular those that arosed in the process of Chernobyl New Safe Confinement designing. The publication contains a wide bibliography.

ISSN 2410-2547 Опір матеріалів і теорія споруд/Strength of Materials and Theory of Structures. 2020. № 104 4 structural mechanics, theory of elasticity and theory of plasticity (strength disciplines) and general sections of the engineering analysis of the bearing structures. Many of these disciplines are actively engaged in their own lives, naturally, serving the theory of structures, but often focused on some of the internal problems of general scientific orientation. So, to the theory of structures that is adjacent (but, in our opinion, are not included as part of) to the analysis of mechanical properties of structural materials, as well as such problems of mechanics of solids as the mathematical theory of elasticity, theories of plasticity, thermoelasticity, thermoplastic elasticity, etc. There is no clear boundary, but in this review we will not enter any seriously on "neighbouring territory".
The emergence of the Kyiv scientific school of the Theory of structures is associated with the establishment in 1899 at the newly organized Kyiv Polytechnic Institute 3 (KPI) the Strength of Materials Department.
Further, the formation and development of the theory of structures was facilitated by the creation in 1918 of the Ukrainian Academy of Sciences, the Institute of Mechanics of the NAS of Ukraine, expansion of relevant research in higher education institutions, creation of new academic and sectoral research institutions. This review presents the substantive side of these studies. The bibliography is quite extensive.
When selecting quoted sources, monographic publications are indicated first. References to articles in periodicals, as a rule, represent specific examples and are not exhaustive lists of sources. The accents in the thematic selection, of course, are determined by the interests of the authors, are open to expansion and do not pretend to be ranked according to the importance of certain problems.
The authors hope that the book will be useful and will evoke pleasant memories for many students of the Kyiv School, who now work fruitfully in many countries of the world.
Studying the history of knowledge helps to familiarize the reader with historically objective evaluations of certain research results and priorities, to realize the sometimes long and extraordinarily thorny path of formation even small and obvious scientific achievements and truths. Equally important, it helps to reflect that atmosphere of deep mutual respect and goodwill which, despite the lengthy and intense discussions, has prevailed and should prevaile in the scientific community of modern society.
The authors of the work are graduates of Kyiv Civil Engineering Institute (now Kyiv National University of Construction and Architecture), which celebrates its 90th anniversary in 2020. The authors dedicate this publication to this significant event, as well as the blessed memory of their dear teachers and colleagues.

FIRST STEPS
An outstanding scientist and organizer of engineering education, the first Rector of the KPI Professor Emeritus V.L. Kirpichov clearly understood the need for radical reform of higher engineering education in accordance with urgent demands of industry, as well as the development of mechanics in general and structural theory in particular (and he was personally interested in this section of mechanics) in physics and technology direction.
In 1899, a year after the opening of the Institute, V.L. Kirpichov began to lecture at the Strength of materials Department on a wide range of strength disciplines [Ошибка! Источник ссылки не найден., Ошибка! Источник ссылки не найден., Ошибка! Источник ссылки не найден.] (strength of materials, graphical statics, etc.). His classic work [Ошибка! Источник ссылки не найден.] presented the theory of statically indeterminate structures in a very compact and transparent way and completed the period of the theory of structures formation in Russia.   On the initiative of V.L. Kirpichov many talented scientists from different universities of the former Russian Empire was invited to KPI. Among them were the bridge building specialist Professor Yevgeni Oscarovych Paton and specialist on the mechanics of materials and structures Professor Stepan Prokopovych Timoshenko. It was they, together with V.L. Kirpichov, who laid the Foundation of Kyiv scientific School of mechanics.

Kirpichov Viktor Lvovych
By the time of moving to Kyiv, Ye.O. Paton published the first volume of his four-volume course "Iron Bridges", as well as the work that played an important role in the theory of structures [Ошибка! Источник ссылки не найден.]. In this work, a study was carried out, revealing the conditions under which it was possible to use a hinged design scheme of a truss, nodes of which were not perfect hinges. A notable influence on the development of the theory of structures was made by the studies of Ye.O. Paton, dedicated to the "laws of weight" of bridge structures [Ошибка! Источник ссылки не найден.].    (1896). He taught at the Moscow engineering school of communications (1899)(1900)(1901)(1902)(1903)(1904), at the Kyiv Polytechnic Institute  and at the Kyiv construction College of railway transport. In 1909In -1911   Combining teaching with practical engineering, E.O. Paton had already done a lot in the 1920s: according to his projects, bridges were built in Tiflis (Tbilisi), two bridges across the Ros River, a pedestrian bridge across the Petrivska alley in Kyiv. The third and fourth volumes of his fundamental work "Iron Bridges" were published, as well as a separate no less serious work "Wooden Bridges". In 1917, as many as two textbooks, one atlas of drawings, and nine scientific articles appeared from his pen. The Kyiv bridge named after Eugenia Bosch ( Fig. 1) was restored under his leadership. Yevgenii Oskarovych ran the Kyiv test station of the Central institute of structures of the People's Commissariat for Railways, and did a great job of summarizing the test results on operated and restored railway bridges.

Paton Yevgenii Oscarovych
In particular, an assessment of the errors that occur due to neglecting the rigidity of the nodes, when calculating bridge trusses, by comparing the data on the measured stresses with their calculated values was made [319]. Interesting data were also obtained while testing the bridge, specially designed and built by the Kyiv test station for experiments [324].
Together with his student B.M. Gorbunov, he continuously improved his multi-volume course of steel bridges, which was published in several editions and was a true encyclopedia of bridge building, in which the issues of structural resistance were presented in an exhaustively detailed form.  -Professor, Academician of the Ukrainian Academy of Sciences (1918), Foreign Member of the Academy of Sciences of the USSR (1964, Corresponding Member, 1928. Honorary member of the Academies of Sciences, Scientific Societies, Honorary Doctor of the most famous universities in many countries of the world. In 1901 he graduated from the St. Petersburg communication engineers institute.

Timoshenko Stepan Prokopovych
In 1906 he defended his dissertation. In 1906In -1911In , 1918In -1920 (1927). In 1927-19361936-1943-Head of the Department of Mechanics, 1943-1960  Combining teaching with active research, S.P. Timoshenko received a number of outstanding results on various issues of strength analysis [451,450,452,448], including those in a series of studies on the theory of the elastic systems equilibrium stability [453,454,455,456]. The work [Ошибка! Источник ссылки не найден.] was awarded the D.I. Zhuravsky prize and medal. In 1908 S.P. Timoshenko published a textbook on the strength of materials [449,458], which became a classic and was later reprinted many times in many languages of the world. The problem of lateral buckling of beams with narrow rectangular cross-section was first considered by Prandtl. Further development of this problem belongs to Timoshenko, who in 1905-1906 obtained the basic differential equation for the torsion of symmetrical Ibeams and on this basis investigated the lateral buckling of transversely loaded high I-beams [457]. This study by S.P. Timoshenko was later represented at the Kyiv Polytechnic Institute for the adjunct in applied mechanics degree defense (the opponents were V.L. Kirpichov, A.A. Radtsig and N.B. Delone).
But the main thing is that S.P. Timoshenko turned the Prandtl academic problem into a problem of great importance for the practice of bridge engineering. In connection with the problem of spatial buckling, the issue of torsional loss of stability, which was also considered by S.P. Timoshenko [457], became very important.
It should be noted that in solving this problem S.P. Timoshenko found that the Saint-Venant principle is not applicable for torsion of an I-beam. The twist angle depends not only on the magnitude of the torque and the torsional rigidity of the beam, but also on the way of fixing its ends (Fig. 2).
In [455] S.P. Timoshenko considered the problem of buckling of rectangular plates, under various conditions of supporting the edges parallel to the acting compressive forces. He also considered the buckling of rectangular plate whose unloaded side is unrestrained.

ORGANIZATIONAL ACTIVITY. FOUNDATION OF THE UKRAINIAN ACADEMY OF SCIENCES. S.P. TIMOSHENKO INSTITUTE OF MECHANICS OF THE NAS OF UKRAINE
S.P. Timoshenko did a great deal of organizational work. From 1909 to 1911 he was dean of the mechanical and engineering departments. From the post of dean, he, along with two other deans of the KPI, was dismissed by order of the Minister of Education Kasso for refusing to dismiss Jewish students who had been accepted in excess of the so-called "percentage rate". Returning to Kyiv in 1918, S.P. Timoshenko took an active part in the work of the V.I. Vernadsky commission drafting a law on the establishment of the Ukrainian Academy of Sciences.
S.P. Timoshenko's participation in the creation of the Ukrainian Academy of Sciences should be especially noted. After the collapse of the Russian Empire, the Ukrainian Scientific Society (USS), created in 1907 in Kyiv and headed by M.S. Grushevsky, at a joint meeting on July 8, 1917 formed the Commission for the establishment of the Ukrainian Academy of Sciences. And on April 3, 1918, the USS addressed to the Ministry of Education of the Ukrainian People's Republic (UPR) with a proposal to consider the possibility of financing the work of reorganization the USS into the Ukrainian Academy of Sciences. National Academy of Sciences on the concept of M.S. Grushevskogo was to become a non-governmental institution without its own scientific institutions.
Almost at the same time, another concept of creating a national academic center emerged. In September-October 1917 in Petrograd, N.P. Vasilenko, who was a friend of the Minister of Public Education of Russia, together with V.I. Vernadsky, who was also a fellow of the Minister of Education of Russia, and others advocated the creation of state-owned research organizations in Ukraine, Georgia, and Siberia.
For the organization of the Ukrainian Academy of Sciences (UAS) M.P. Vasylenko invited V.I. Vernadsky, who was in Poltava during this period. The famous organizer of science V.I. Vernadsky was a supporter of the creation of a state network of research institutes. He, as a man of advanced views, openly believed that "the task is not a state organization of science, but state assistance to the scientific creativity of the nation." On June 7, V.I. Vernadsky discussed the creation of the UAS with M.S. Grushevsky, who stood on the principles of building the UAS as a free union of high scientific authorities. His position was against the concept of Vernadsky-Vasylenko. The same thing happened with respect to the staff and direction of the UAS. V.I. Vernadsky insisted on creating the "Academy of Ukrainian Studies", at least at the initial stage. M.S. Grushevsky himself categorically refused to participate in any activities proposed by the government of P.P. Skoropadsky.
The The Commission identified the fundamental problems associated with the development of the structure of the Academy and the composition of its departments, a list of departments, scientific institutions, and the procedure for their formation. At this meeting, they came to the conclusion that the  (1873 -1945) appointment of the first Academy staff by the highest authority is logical, given that the UAS was created by the state. The initiative group, headed by V.I. Vernadsky instructed S.P. Timoshenko to make a report on the organization of the unit of applied sciences in the physical and mathematical department of the Ukrainian Academy of Sciences. The idea of bringing science closer to the demands of life has always been attractive to S.P. Timoshenko, and he joyfully and with great interest began to compose a note.
S.P. Timoshenko wrote in the introductory part, "A characteristic feature of the modern development of industry and technology is the widespread use of the scientific method and the facts gathered by science. The times when science and technology have taken different paths is over, and now they often use the powerful tool that mathematics and mechanics give us to solve purely technical problems. They use the methods of experimental sciences and widely adapt them to solve technical problems in the laboratory. … The Academy of Sciences should take the initiative in combining science and technology. Due to its central position and scientific authority, it will be able to gather around itself the few scientific forces that currently exist in Ukraine and combine them in a common work where cooperation between people of technology and science will be possible." S.P. Timoshenko further noted that "representatives of technical science will be able to use scientific methods and knowledge accumulated by pure science to a greater extent than now. On the other hand, representatives of pure science in the field of applied natural sciences will encounter a number of new, unexplored issues, the solution of which will not only enrich science, but will also contribute to the development of industry and the technical life of the region. In the field of experimental activity, people of science will be able to use those powerful tools that modern technology gives into the hands of the experimenter." S.P. Timoshenko believed that the newly formed Ukrainian Academy of Sciences should pay more attention to combining pure science with the solution of technical problems, in accordance with the needs of technology.
The commission completed its work on the draft law on the creation of the Ukrainian Academy of Sciences on September 17, and on October 12, the Minister of Education and Arts N.P. Vasilenko submitted a package of documents to the Council of Ministers. On November 14, 1918 Hetman of Ukraine P.P. Skoropadsky approved the "Law of the Ukrainian State on the Formation of the Ukrainian Academy of Sciences in Kyiv" adopted by the Council of Ministers, as well as the Charter and staff of the Academy and its institutions attached to it.
In the period from November 1918 to January 1919, the UAS carried out active scientific and organizational work. The Department of Physics and Mathematics of the UAS consisted of 14 departments of the main class and 16 departments of the class of applied natural sciences.
At this time, academic departments of the physics and mathematics subdivision were founded, including the Department of Applied Mechanics, which was headed by S.P. Timoshenko. At the same time, elections and approval in the posts of directors were held. On November 27, 1918, the first General Meeting of the UAS was held, at which V.I. Vernadsky was elected Chairman-President of the Academy. And at the second General Meeting of the UAS, which held on November 30, the Institute of Technical Mechanics of the UAS was formed and S.P. Timoshenko was approved as its director. During the first decade of its existence, the institute occupyed a leading place in the physical and mathematical subdivision.
In 1929  Actually the entire history of the development of the institute, on the basis of which a number of other independent scientific institutions of the Academy of Sciences of the Ukrainian SSR was created, is based to some extent on the principles laid down by S.P. Timoshenko at the dawn of the emergence of Ukrainian academic science. It is worth recognizing that the ideas expressed by him almost a hundred years ago during the organization of the Ukrainian Academy of Sciences turned out to be quite progressive and embodied in practice. The experience of the first Ukrainian Academy of Sciences, where technical sciences were included in the number of academic sciences for the first time in world practice, was later spread in the practice of the USSR Academy of Sciences and in all other republican academies. Ideas of S.P. Timoshenko, laid down by him during the creation of the Ukrainian Academy of Sciences, over time having received further development, today contributes to the widespread implementation of the results of scientific achievements in practice.
Today, Ukraine has a high world level of development of mechanics and related sciences.
The level of science is determined, for example, by the existence of the Department of Mechanics and a number of scientific institutions at the National Academy of Sciences of Ukraine. These are such well-known in world science institutes as S.P. The main tasks of the NCU are: preparation and holding of scientific forums on theoretical and applied mechanics and related sciences; facilitating the coordination of scientific research on selected issues of mechanics conducted by scientists in various institutions, departments and industries; strengthening the relations of Ukrainian mechanics with foreign scientists, as well as organizations and international societies with the aim of developing mechanics; spread of scientific and technical information on mechanics; representation of Ukrainian mechanics at the International Union of Theoretical and Applied Mechanics (IUTAM) and other international organizations in mechanics and related sciences.
IUTAM was organized on September 22, 1946 at the constituent assembly of the world's leading mechanics at the Sorbonne University in Paris and is currently the most prestigious scientific union in the field of mechanics. It is appropriate to indicate that world physics is united into the International Union of Pure and Applied Physics -IUPAP.
Second most important after IUTAM is the European Mechanics Society, this society assumes only the personal membership of scientists. NCU is an affiliate of IUTAM (in total, 55 countries in which mechanics have reached a certain level of development are affiliated members). In 2000 at the session of the IUTAM General Assembly in Chicago (USA), following a vote, Ukraine was admitted to IUTAM. O.M.Guz was elected representative of Ukraine in the General Assembly.
NCU promotes the development of all important and relevant areas of basic research in the field of mechanics and related sciences, using various means (support for publications in the international scientific journal International Applied Mechanics, discussion at scientific seminars and scientific conferences, etc.).
In total, the NCU currently consists of 282 members -doctors of sciences in mechanics and related branches of science, who represent approximately equally academic and university science.
NCU is the only all-Ukrainian public organization that brings together scientists from all areas of Ukraine working in the field of mechanics and related sciences, and which creates a platform for discussing all the important problems of the development of mechanics and related sciences. The influence of NCU members on scientific research in the field of mechanics is dominant and determining.
The activity of the NCU is aimed both at maintaining the world level of development of mechanics achieved by previous and modern generations of Ukrainian scientists, and at developing new areas of mechanics (for example, nanomechanics, biomechanics, tribomechanics, etc.)