Напружено-деформований стан і несуча здатність трубобетонних елементів зі зміцненими осердями

Паливода О.А. Напружено-деформований стан та несуча здатність трубобетонних елементів зі зміцненими осердями. – На правах рукопису. Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.23.01 – будівельні конструкції, будівлі та споруди. – Національний авіаційний університет, МОН України, Київ, 2016. В дисертації наведено результати експериментально-теоретичних досліджень з розв’язання актуальної теми – виявлення особливостей деформування та дійсної роботи елементів з різними способами зміцнення їх ядер. Визначені експериментально впливи різних конструктивних схем на деформативність та несучу здатність розглянутих елементів. Розроблено аналітичні та чисельні методи оцінки напружено-деформованого стану і методику розрахунку міцності досліджуваних конструктивних елементів. Наведено наочний приклад застосування одного з-поміж запропонованих конструктивних рішень досліджуваних конструкцій в галузі промислового будівництва. Ключові слова: трубобетон, зміцнене осердя, напружено-деформований стан, несуча здатність, деформації, чисельні методи, аналітичні методи.Palyvoda O.A. State of stress and deformation and carrying capacity of tube confined concrete elements with strengthened core. – Manuscript copyright. PhD Thesis on speciality 05.23.01 – building structures, buildings and constructions. – National Aviation University, MSE of Ukraine, Kyiv, 2016. The thesis presents the results of experimental and theoretical studies to address relevant topics - identifying features of deformation and actual operation of the elements with a variety of ways to strengthen their cores. The influence of various constructive schemes on deformability and carrying capacity of the considered elements is experimentally determined. In the introduction the relevance, scientific novelty and practical significance of the work are provided, its general characteristics are given. Particularly it is noted that tube confined concrete constructions have been widely spread in the world construction practice because of its positive qualities. Using the methods of strengthening cores will give an opportunity to get even more technical and economic effect. The first part provides an overview of the literature and analyzes the question on research devoted to theoretical and experimental investigation of tube confined concrete structures. Characteristics of constructive solutions for strengthening their cores are given. According to the analysis of literary sources, conclusions are made, the essence of the problem is disclosed and research problems are stated. The second part is devoted to a description of the experimental tests program, the purpose of which is to establish the characteristics of the parameters change of stress and deformation state and determining the carrying capacity of the elements being considered. The third part of the thesis deals with the results of experimental studies of compressed short tube confined concrete elements with strengthened cores. The studies found that the carrying capacity of the tube confined concrete elements with strengthened cores under axial compression is mainly influenced by the following factors: the strength of the concrete core, the thickness of the tube wall, the thickness of the concrete layer and the diameter of the tube. It is found that the efficiency of tube confined concrete operation, determined by the coefficients m and η, decreases with increasing strength of concrete class, the tube diameter and increases with increasing tube wall thickness. The carrying capacity of the considered tube confined concrete elements with strengthened core exceeded of approximately 1.5 ... 3 times the carrying capacity of the elements of the steel tubes not filled with concrete at the same altitude of samples applied load. The graphs of dependence of the development of relative longitudinal and transverse deformations on the magnitude of compressive force are made. The fourth part is devoted to numerical modelling of stress and deformation state of central compressed tube confined concrete elements with strengthened cores. The algorithm for calculating with the finite element method on computing machine is adapted. The presented comparison of the results of experimental and numerical studies has shown divergence approximately equal to 7 %. The fifth part is devoted to analytical modelling of stress and deformation state of central compressed tube confined concrete elements with strengthened cores. The analytical calculation algorithm is adapted using iteration modulus of concrete elasticity. The option for determining the carrying capacity of tube confined concrete elements with strengthened cores by bringing a comprehensive cross-section to the steel item is presented. The presented comparison of results of experimental and numerical studies has shown divergence approximately equal to 8 %. The implementation of research results in the design and construction of industrial facilities is presented. The conclusions formulated the achieved results, reflecting the scientific novelty and solution of the important scientific and technical problem – the creation of calculation and design methods for advanced tube confined concrete constructions with strengthened core