Abstract: The method of calculating the shells of revolution for an asymmetric load using a semi-analytic finite element method is considered. An example is given of calculating a corrugated cylindrical tank for wind load. Comparison of meridional and annular forces is performed for a smooth and corrugated shell of identical dimensions.
Abstract: In the constructions of multilayer cylindrical shells in heat-and-power engineering the materials, exhibiting rheological properties, such as concrete, polymers or fiber glass are widely used. In this connection, the study of temperature stresses in polymers, the analysis of the influence of various factors on the processes course under consideration, is of great importance. The paper presents an analytical solution of the thermal creep problem in polymers using the Kelvin-Voigt model for a rigidly clamped rod for various cases of temperature loading. The analysis of these solutions is also made on the example of a specific material for certain laws with changing temperature loads.
Abstract: One of the main problems in a design of rigid bus structures in open switchgears devices is a structural stabilization under the influence of various dynamic loads. The implementation of rigid bus structures with large spans of pipe-bus showed a real danger of the wind resonance for cylindrical pipe-bus structures (aeroelastic oscillations). This phenomenon is dangerous in that at low wind speeds there are intense pipe's oscillations in vertical plane, adding to the static loads an essential dynamic component. Its level is comparable with the loads from the weight of the structures and can, in combination with the rest loads, cause stresses close to the maximum admissible for the 1st group of limit states. The problem of reducing the level of structural oscillations in many cases is associated with the need to increase the rigidity and reduce the material consumption, but it's important to meet the technological requirements imposed by operating conditions and protect people from harmful vibration. In a paper are considering a new method for damping oscillations for rigid bus structures under the action of a wind vortex excitation – damper as a rigid insert. Is presented a mathematical model of the joint work of the rigid bus structure with the damper as the rigid insert. Have carried out analytical researches of the joint work of the rigid bus structure with the damper as the rigid insert.
Abstract: The article shows the process of analyzing and constructing the stiffness matrices for four-node elements in parallelogram and rhombus shapes using the method of potential deformation energy.
Abstract: Increasing pressure in separate areas when reconstructing and improving industrial buildings, may necessarily mean strengthening structural surfaces of buildings. In experimental and analytical assessment hollow cores slabs are represented as T-beams and I-beams. The width of the beam edge decreases according to the dimensions of the voids inside the slab. In this paper the authors test bearing strength and deformability of hollow core slabs in different conditions of strengthening. Furthermore, the scholars perform their calculations in a non-linear system, with a progressive loading, until the samples are destroyed, with a plastic hinge formed in the area extended in a slab cross section. Simulation and figure analyses were designed in ANSYS program. The researchers’ resulting of the stress-strain state of hollow core slabs is observed experimentally at various stages of loading. The researchers compared calculations of slabs with the full-scale cross section shape and calculations of the same I-beam slabs. Though, the investigators dwell on the impact of the cross-section on the results of the maximum slab deflections. The paper is also dedicated to a variety of strengthening modes and it explains that the cracking point for full-scale slabs comes after.
Abstract: The Stress and strain state of building structures in zones with bird's mouths and cuts of the boundary is characterized by stress concentration zones emergence and requires an evaluation of strength and reliability of objects, which is the engineering practice actual task. Theoretical analysis of stress and strain state of bird's mouth areas of the region boundary is confined to the study of singular solutions of the elasticity problem with power singularities. In this case, the concept of stress or strain concentration at an irregular point of the region boundary becomes meaningless. In the present article, stress and strain state is considered in the neighborhood of the bird's mouth vertex of the boundary of a plane region, which is written with the help of the intensity factors. Two approaches are given to obtaining the expressions for displacements, stresses in the neighborhoods of an irregular point of the boundary of a plane region by means of stress intensity factors and strain intensity factors. The difference in the expressions for stresses and displacements obtained for the limiting values of stresses and strains determines the practical significance of the work during the experiments and the determination of the critical values of stresses and strains.
Abstract: The article proposes applying energy from law deformation mechanics of the rigid body to deformation method for calculating the strength of reinforced concrete constructions with the use of diagrams illustrating the deformation of concrete and reinforcement. In terms of the energy theory of strength, concrete and rebar accumulate potential energy in the section of the construction component under stress; based on the contours of the diagram used in calculation it is possible to distinguish a stress diagram for concrete of the compressed zone. The value of the strains is equivalent to the force used for the deformation of the concrete specimen under stress (prism-or cylinder-shaped); the force is equal to the area used in the calculation of the normable diagram. The resolving balance equations are deduced with the use of the flat section hypothesis. The conditions of the stress balance in the section of the construction component are tested with the method of the successive approximation. The variable parameter of approximation is the construction component bending. General deformations (deflections) of the construction components are significantly higher than their limit stress values permitted for safe operation.
Abstract: The problem of natural oscillations of an elastic thin non-circular cylindrical wavy shell of an open profile is considered. The problem is based on the Rayleigh-Ritz energy method. On the basis of the proposed method for determining the lowest frequencies and forms of natural vibrations of shells of complicated shape, the numerical convergence of the developed algorithm is investigated. The evaluation of the results of this numerical experiment is given.
Abstract: Free and forced longitudinal oscillations of homogeneous rods of constant cross section are considered. Analytical and numerical methods for solving problems are used. With free vibration, numerical examples are shown for a rod with a jammed and free end and for a rod with a concentrated non-deformable mass at the end, due to which the mathematical model accordingly changes. Forced oscillations are considered for distributed and concentrated loads. The eigenmodes of oscillations characteristic for continually discrete sisites are obtained.