Azerbaijan National Academy of Sciences

-         specialty code

-         specialty name

-         topic name

3305.03

Building structures, buildings and constructions

Oscillation of Offshore Stationary Platform Support Blocks Considering Foundation Compliance

-          number of scientific publications printed abroad:

-          number of papers  published in journals indexed and abstracted in international databases

39

15

5

-         number of  PhD

Author of 7 significant scientific results in engineering sciences from 2003 to 2026:

1. One of the most important issues in the field of stress-strain state and load-bearing capacity of Offshore Stationary Platforms (OSP) is examined, namely, ensuring the rigidity, reliability, and stability of OSP during operation in various climatic conditions and at different depths. The following results were obtained:

-As a result of the technological process, in full compliance with design and manufacturing technology requirements and maximum utilization, reliable results were obtained for measuring the characteristics of the structure's stress-strain state under multiple test loads in accordance with quasi-static and dynamic loading schemes.

- The actual dynamic deformation of the OSP support block structure under load was determined, eliminating the repeated impact of the disturbing force on the model's movement. Based on the experimental results, the amplitude-frequency characteristics of the model's natural vibrations were determined.

- Analysis of changes in the amplitude-frequency characteristics of the support block at various levels of creep of the support plane showed that these changes are nonlinear in nature. The most important characteristic when calculating hollow structures taking into account wave effects is the period of natural oscillations.

- Experimental studies revealed that the numerical values of the parameters characterizing various OSP loading schemes vary depending on many nonlinear factors.

- Repetitive laboratory tests conducted on a OSP model on a viscoelastic foundation and real piles revealed nonlinear changes in the block's natural frequencies. In this case, nonlinear deformation of the foundation is supplemented by nonlinear deformation of the structure.

It was found that existing methods for calculating the dynamic deformation of the OSP support block cannot provide completely reliable results, since they assume linear effects and linear responses as deterministic.

Co-author: V.A. Shekhovtsov

2. A rapid seismodynamic method for determining object characteristics is proposed. This method eliminates the need for complex measurements and research on the surface and underwater to assess the technical condition of offshore hydraulic structures at oil and gas fields and the feasibility of their continued safe operation.

The following results were obtained:

- The proposal is based on an analysis of theoretical and experimental results of Oulman seismodynamics. A methodology for its application, validated by tests for rapid assessment, is presented.

- Using the finite difference method, one of the most advanced methods in engineering calculations, a system of algebraic equations was constructed for finding deflections at given pile design points with changes in the soil stiffness coefficient and the pile bending stiffness. This system can be effectively used in engineering calculations. Formulas for determining contact stresses were derived.

-A new methodology for studying the stress-strain state of piles was developed, and an algorithm for its solution was created.

- During the study of platform No.1, the capabilities of the proposed seismodynamic method for the operational assessment of the technical condition of the structure were tested;

-A comparative analysis of the results of applying the developed seismodynamic method to the structure of Platform No.1 was conducted with the results of a strength report compiled based on comprehensive measurements and research conducted in the underwater and above-water sections of the platform, confirming the potential of the presented method for adequately assessing the technical condition of the structure.

- The application of the developed method by operators and supervisory authorities for periodic operational monitoring of the technical condition of hydraulic structures in accordance with current safety legislation and operating standards was proposed.

- A system for solving algebraic equations for determining deflections at pile design points in the event of arbitrary changes in the soil stiffness coefficient and pile bending stiffness using the finite difference method was developed. - Formulas for calculating the ordinates of the internal forces arising in the pile and the contact stress arising between the pile and the soil during horizontal impacts are provided.

-Since the solution algorithm has a general structure, it is possible to study the influence of the pile flexibility coefficient, which plays an important role in design, on the stress-strain state of the pile.

3. An effective numerical method for determining the stress-strain state and bearing capacity of a tubular concrete element for arbitrary values of plasticity and compressive force eccentricity has been developed, along with a corresponding software module implementing this calculation method with any specified accuracy.

The following results were obtained:

Based on the numerical experiments, it was established that the calculation of compressed tubular concrete elements should be performed using real nonlinear material deformation diagrams; otherwise, the obtained results will not reflect the actual deformation of the element;

- The proposed calculation method allows for the use of a single method, unlike the standard calculation method, which incorporates the concepts of "long," "short," and "elements compressed with small eccentricity" and "elements compressed with large eccentricity." It is possible to determine the stress-strain state and bearing capacity parameters.

4. One of the most important issues ensuring the strength, reliable stability, and long-term operability of hydraulic structures is their anchorage to the seabed. For theoretical calculations, the values of relative deformations and displacements were determined based on experimental results under various load combinations:

-By comparing theoretical and experimental results, the numerical value of the critical load of the compressed-flexural complex element of the OSP support block was determined with sufficient accuracy, which is accepted in engineering practice.

- A universal program for calculating the stability of compressed-flexural rod complexes using computational methods is proposed, which, when applied in practice, can be very effectively used in engineering calculations.

- The calculation results of the proposed program correspond to numerical estimates obtained from experimental studies of samples characterized by a completely nonlinear deformation process.

- From the extensive and highly accurate analysis of experimental results, it is clear that the limiting value of loads at any stage of their increase coincides with the practically permissible accuracy of the parameters found by the proposed calculation method, and can be widely used in practice.

5. Modeling methods for determining the load-bearing capacity of the supporting structure of the OSP were considered. This method replaces natural learning with the study of a similar model state taken at a specific scale, and an effective and appropriate scale of 1/10:1/5 was chosen.

The following results were obtained:

- Numerous studies have shown that the supporting blocks of a spatial pile system can be modeled using the principle of complete geometric similarity or by preserving only the ratio of the stiffness characteristics of the system elements.

- One of the most important issues is ensuring the characteristics in models of different scales depending on their size and manufacturing method. It was found that non-profiled electric-welded joints of the model elements possess sufficient load-bearing capacity.

6. Creating an experimental foundation model corresponding to the actual operation of piles in soil is a complex task, so a simplified foundation model was used. Mechanical modeling allows for a virtually complete and satisfactory match between the deformation properties of the model and the foundation, and the modeling was conducted in accordance with a specified algorithm. The design of the OSP model and dynamic testing equipment were selected, and the devices used in the tests and the installation technology were identified and implemented in accordance with the plan.

As a result, a significant influence of the OSP on vibrations was established:

- Analysis, research, and comparisons revealed that the mathematical model describing the dynamic movement of the OSP can account for not only linear wave effects but also nonlinear deformation of the soil base, as well as the structure as a whole as a structural design.

- Experimental studies of the dynamic movement of a small-scale OSP foundation model at a scale of 1/16 were conducted, the main goal of which was to determine the specific vibration frequency, free vibration modes, and vibration damping.

- Experimental studies were conducted to determine the model's key dynamic characteristics based on excitations with various types of oscillations.

- Schemes were developed to determine specific model oscillations corresponding to the excitation pattern.

- By analyzing the experimental results, the frequency and amplitude of periodic forced oscillations in the model structure were determined.

-Numerous studies revealed a significant reduction in the natural oscillation frequencies of a model partially secured to a foundation, compared to a model rigidly clamped to the foundation by the supporting block.

-The results of experimental studies of forced oscillations of the model using a vibrator allowed for an approximate determination of the natural frequency values.

- Considering that creating an experimental model corresponding to a real nonlinear model of pile deformation in soil is extremely difficult and, as a rule, impossible, a simplified model was used to simulate the nonlinear response of the soil and the long-term consolidation process. In this model, consolidation processes and nonlinear reactions are simulated only in the direction of the supporting block axis (the vertical direction).

- Experimental studies were conducted to determine the natural oscillations of a model of a OSP supporting block on a viscoelastic foundation, and based on the analysis of the results, graphs of the oscillation frequency change over time were constructed. A satisfactory agreement was found between the oscillation frequency changes in the real and model piles.

- Theoretical and experimental studies using this methodology yielded reliable results for the characteristics determining the stress-strain state of the structure under various types of loads. This methodology allows for the determination of the actual dynamic deformation of the OSP support block structure.

-The change in characteristics at different levels of block plane creep is nonlinear.

- Most existing methods fail to yield reliable results because they rely on the concept of linear effects and linear responses when calculating the dynamic deformation of the OSP support block.

-Experiments determined how changes in the attachment of the block supports to the foundation under various conditions affect its dynamic mobility and the importance and sensitivity of this process for accurately determining the overall stress-strain state.

7. A solution to important engineering problems was achieved using an effective and practically relevant numerical method and software module for determining the stress-strain state and load-bearing capacity of tubular reinforced concrete elements for various values of ductility and compressive force eccentricity. It was established that when applying methods for assessing the stress-strain state of tubular reinforced concrete elements, which are widely used in engineering, and when determining their load-bearing capacity, actual nonlinear material deformation diagrams should be used; otherwise, the results will not reflect reality.

1. Самедов Ф.С., Махмудов М.С. Экспериментальное исследование прочности обетанированных труб в зависимости от состава бетонных смесей и технологии укладки подводных трудопроводов. Труды ВНИПИГАЗ по добыче нефти и газа, транспорту продукции, обустройству морских нефтяных и газовых месторождений. Баку, 1983,p.78-87.

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2. Самедов Ф.С., Махмудов М.С., Алиев Ф.И., Мастанзаде Н.С. Натурные испытания узловых соединений опорных блоков морских стационарных платформ на моментную нагрузку. «Расчет строительных конструкций на статические и динамические нагрузки». Межвузовский тематический сборник трудов, Ленинград, 1985, p.7

https://www.researchgate.net/ publication/381295284

3. Ахмедов Я.Э., Махмудов М.С., Алиев Ф.И. Исследование модели глубоководных морских платформ на горизонтальную нагрузку.  Всесоюзная конференция “Комплексное освоение нефтегазовых ресурсов континентального шельфа СССР”, Москва, 1986 г., p. 2.

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4. Решетчатые конструкции с нелинейно-ползучим основанием. Всесоюзная конференция “Комплексное освоение нефтегазовых ресурсов континентального шельфа СССР”, Москва, 1986, с.2.

https://www.researchgate.net/ publication/381295384

5. Взаимодействие опоры блока МСП с нелинейно-ползучим основанием Межвузовский тематический сборник ЛИСИ по проблемам расчета строительных конструкций с учетом физической и геометрической нелинейности. Ленинград, 1986 г., p.8.

https://www.researchgate.net/ publication/381232746

6. Мамедов Б.М.,Ахмедов Я.Э., Махмудов М.С., Алиев Ф.И. Статистические экспериментальные исследования конструкций крупномасштабной модели опорного блока морской стационарной платформы с различными условиями закрепления опорных ног. Всесоюзное научно-техническое совещание. Экспериментальные исследования и испытания строительных металлоконструкций.  ЭИИ СМ-87, с.2

7. Ахмедов Я.Э., Махмудов М.С. Экспериментальные исследования по определению динамических параметров конструкции крупномасштабной модели опорного блока морской стационарной платформы Всесоюзное научно-техническое совещание. Экспериментаные исследования и испытания строительных металлоконструкций. ЭИИ СМ-87, с. 2

8. Алиев Ф.И., Гулиев Т.С. Универсальный стенд для проведения экспериментальных исследований узлов глубоководных стационарных платформ натурных размеров Информационный листок о научно-техническом достижении № 87-043, с.3

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9. Ахмедов Я.Э., Махмудов М.С.,Алиев Ф.И.,Экспериментальные исследования прочности и деформативности узлов и элементов конструкций морских сооружений. Межвузовский тематический сборник трудов по прочности, устойчивости и колебаниям строительных конструкций. Ленинград, 1987 г., с.3

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10. Лебедев В.А., Санжаровский Р.С.,Зиновьев Н.Г., Дерябин И.С., Ахмедов Я.Э., Суворов А.В. Экспериментальные исследования модели опорного блока МСП № 16 на свободные колебания в натурных условиях. Депонированная статья ВНИИНТПИ, Москва, 1988 г., с.6

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11. Лебедев В.А., Санжаровский Р.С., Зиновьев Н.Г., Дерябин И.С., Суворов А.В., Некоторые итоги экспериментальных исследований модели опорного блока МСП на динамические воздействия.  Депонированная статья ВНИИНТПИ, Москва, 1988 г., с. 8

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12. Теоретическое определение частоты собственных колебаний опорного блока МСП с учетом нелинейного деформирования основания. Депонированная статья ВНИИНТПИ, Москва, 1989 г., с.  45

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13. Экспериментальное определение частоты собственных колебаний модели опорного блока МСП с учетом нелинейного деформирования основания.     Депонированная статья ВНИИНТПИ, Москва, 1989 г., с.28

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14. Ахмедов Я.Э., Исаев И.М.  Способ динамических испытаний пролетных строений.  Авторское свидетельство № 1769056 от     15 июня 1992 г., выданное Госкомизобретений СССР. https://www.researchgate.net/ publication/381232388

15. Экспериментальное исследование колебаний опорного блока МСП с учетом нелинейного деформирования основания. Труды молодых ученых СПбГАСУ, Часть II Санкт-Петербург, 2001 г., с.4

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16. Колебание морских стационарных платформ с учетом нелинейного деформирования основания. Труды молодых ученых СПбГАСУ, Часть III Санкт-Петербург, 2001 г., с. 4.

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17. Результаты экспериментальных исследований колебаний опорного блока МСП. «Азербайджанское нефтяное хозяйство», Баку, 2002 г. № 5,  s.25-27 

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18. Определение динамических параметров при использовании буровой вышки в качестве гасителя колебаний МСП. «Азербайджанское нефтяное хозяйство», Баку, 2002 г. № 5, s.33-35,

19. Шеховцов В.А. Несущая способность морских стационарных платформ.Санкт-Петербург, 2003 г. (Монография), с. 349

20. Определение частот нелинейных собственных колебаний опорного блока МСП на недеформируемом основании. Научные труды АЗНИПИ нефти, 2005 г., № 4, с.3

21. Разработка метода расчета опорного блока на основе эквивалентных модулей деформaции. Санкт-Петербург, «Строитель», № 5, 2005 г., с. 5.

22. Определение частот нелинейных собственных колебаний МСП с использованием метода статистической линеаризации. Баку, «Азербайджанское нефтяное хозяйство» 2005 г. № 11, стр.36, с.5

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24. Использование буровой вышки в качестве динамического гасителя колебаний опорного блока МСП. «Азербайджанское нефтяное хо-зяйство» 2006, №3, с. 3. https://www.researchgate.net/ publication/380940241

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26. Huseynova N.I. The Research of Influence Sea Stationary Platforms Structure Features on Strength Properties of Basic block. Society of Petroleum Engineers SPE Russian Oil and Gas Conference and Exhibition - Moscow, Russia 2010, с. 8. https://doi.org/10.2118/13604 8-MS

27. Əhmədov Y.E., Mustafayev Ş,İ. İsmayılova A.T. Dəniz qurğularının texniki vəziyyətinə operativ nəzarət üsulu. “Azərbaycan Neft Təsərrüfatı” 2022, №10, с. 29-36.

28. М. А. Hadjiyev Svayların üfiqi təsirlərə hesablanması. “Azərbaycan Neft Təsərrüfatı” 2023 М. А. Gadjiyev, U. М. Gadjiyeva Stress-strain state and load ability of compressed pipe-concrete elements

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29. М. А. Gadjiyev, U. М. Gadjiyeva Stress-strain state and load ability of compressed pipe concrete elements. Socar Proceedings, 2023, SI1 p. 5

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30. Y.E. Əhmədov, Ş,İ., Mustafayev A.T. İsmayılova Dəniz qurğularının dinamik möhkəmliyinin təhlükəsizliyinin təminatında rolu. “Azərbaycan Neft Təsərrüfatı” 2023, №2 с. 8 DOI.10.37474/0365 8554/2023-02-37-44

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36. M. A. Hajiyev,  U. M. Hajiyeva, S. R. Bashirzade Structural performance of marine circular reinforced concrete piers under axial loading. SOCAR Proceedings No.2 (2025) 124-134 http://dx.doi.org/10.5510/OGP20250201073

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38. S. R. Bashirzade , O. O. Ozcan , S. R. Bashirzade, M. A. Hajiyev , R. B. Garibov Numerical investigation of crack modeling approaches in the shear design of post-tensioned hollow circular segmental concrete structures

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39. M. A. Hajiyev, , U. M. Hajiyeva, S. R. Bashirzade A novel approach to long-term load-carrying capacity assessment of circular reinforced concrete support structures considering hereditary creep. SOCAR Proceedings No.1 (2026) 116-124.  DOI: 10.5510/OGP20260101159

In 2005, he was awarded a Certificate of Appreciation by SOCAR for his special contributions to the development of the Republic's oil and gas industry.

In 2017, he was conferred the honorary title of "Distinguished Engineer" of the Republic of Azerbaijan (Certificate No. I-383).

In 2021, he was awarded a Certificate of Appreciation by the Republican Committee of the Azerbaijan Oil and Gas Workers' Trade Union for his special contributions to the development of the oil and gas industry.

In 2021, he was awarded the "Honorary Oil Worker" badge of SOCAR for his fruitful scientific and public activities (Certificate No. 421).