22,650 research outputs found

    Geometry and static analysis of thin shells in the form of a diagonal translation surface of the velaroidal type

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    The author presents the results of a study of the geometry and stress-strain state of a surface with a frame of three flat curves in coordinate planes, which have found application today mainly in the shipbuilding industry. The purpose of the work is to identify from the point of view of the stress-strain state from the action of a constant uniformly distributed load the most optimal shell of a diagonal transfer of a velaroidal type with the same main frame of three superellipses. The static calculation was performed using the SCAD program based on the finite element method, designed to perform strength calculations of various types and purposes of structures. The influence of parametric equations for defining a surface depending on the generative family of the same type of cross sections on the distribution pattern of normal stresses and bending moments is shown. The results obtained can help architects and designers with choosing the shape of shells for new projects

    CONSTRUCTION ON EXPANSIVE SOILS: CASE OF ROAD SECTION SÉHOUÈ-MASSI

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    The expansive soils are some soils able to move after loading or water movement; thus, precocious degradations are observed on the structures that are built on them. The present study based on the Sèhouè-Massi section of the Akassato-Bohicon road that is a part of the RNIE N°2 in Benin. The previous work done on the soil of this road section showed that it is on aexpansive clay formation. After had analyzed the auscultation and the geotechnical study results, a road inverse structure appropriate to the traffic was propose

    HISTORY OF THE TOPOGRAPHY IN BENIN: THE OUTSETS OF THE TOPOGRAPHY AND ITS REALIZATIONS IN DAHOMEY (1850 to 1955)

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    The origins of the topography in Benin, (ex French Colony of Dahomey) result from the necessity to the future colonist to know in detail the territory which he desires to establish his military strategy of conquest. Then, the topography came in Dahomey by the missionaries to assist at first the campaign and the military expedition of Danhomey and then to assure the development, the reorganization and the territorial management of the new colony at the be- ginning of 1900s. So the Department of Topography, created for that purpose and animated periodically by different French land surveyors took an important part in the plan of towns and the construction of infrastructures

    Effect of using 3D-printed shell structure for reinforcement of ultra-high-performance concrete

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    This study aims to investigate the effect of 3D-printed polymer shell reinforcemen ton ultra-high-performance concrete. The mechanical properties of ultra-high-performance polymer reinforced concrete have been investigated. At first, the 3D-printed shell reinforcements were designed using 3D Max and Rhino 6 software. Then, each was fabricated through the fused deposition modeling method and positioned into the cubic, cylindrical, and prismatic molds. In the next step, the prepared Ultra-High-Performance Concrete mixture was poured into the molds, and the samples were cured for 28 days. Finally, the compressive, tensile, and flexural strength tests were carried out on the samples. The results indicated that the compressive, tensile, and flexural strengths of reinforced samples were lower than that of the unreinforced ones, respectively. Although including 3D-printed reinforcement decreased the mechanical properties of the Ultra-High-Performance Concrete samples, it changed the fracture mechanism of concrete from brittle to ductile

    Influence of the size of the upper ring on the stressed state of the ribbed-ring metal dome

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    Studies of several metal ribbed-ring large-span domes on computer models have been carried out. All elements of the dome frames are made of steel I-beams. The dome frames have the same number of ribs and rings, but they have different size of the upper ring. The frame elements cross-sections are oriented normally to the dome surfaces, with the exception of the upper ring. The joints of the frame elements with each other are assumed to be rigid in the normal direction and hinged in the tangential direction. The frames are mounted on support nodes at the level of the lower ring pivotally. All the domes are subjected to the same nodal loads from the weight of the enclosing structures and the weight of snow. The snow load is assumed to be asymmetrical, located only on one side of the dome. Under the combined action of these loads, the dimensions of the upper ring of the domes influence the stress-strain state of their frames. As a result of the research, graphs have been generated representing the stress level in the meridional ribs and in the upper rings of the domes. The conclusion has been made that the stress state of metal dome frames depends on the size of the upper ring. The necessity of increasing the cross-section of the upper ring with an increase in its size has been noted

    The development of chart based method for steel beam designs using the Russian sections

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    Introduction and objectives. Russian steel construction does not cover the chart method for steel beam design and experimental works need to be implemented to investigate the behavior of the charts However, the experimental tests are expensive, tedious and time consuming to be conducted. The objective of this paper is to compare and validate the accuracy and reliability of the chart method for steel beam design by correlating moment capacity and bracing length (Φ M n, L b) curves between different sections and this strategy is more helpful in determining the lightest steel sections without trial and error. Materials and methods. Alternatively, a strategy to use the AISC-LRFD's chart-based method, which plots the relationships between the flexural capacities of steel sections and their unbraced lengths of lateral bracing and weights, will be helpful in determining the lightest sections in terms of their lateral bracing requirements and moment capacity. In other words, the most optimum steel sections can be obtained without trial-and-error process. Results. If the design with a chart-based method using the Russian steel sections is developed, it can be used to design steel beams more quickly and economically

    SECOND ORDER STRUCTURAL THEORY FOR THE STABILITY ANALYSIS OF COLUMNS

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    Stability analysis in civil engineering is traditionally centred on the stability of individual components of a structure, rather than on the stability of the assemblage of structural components. This may be explained by the lack of adequate tools for the stability analysis of complete structures in the past. Recently, the necessity of the development of general rational methods of stability analysis with a model of the complex structure is widely recognized. These methods should reliably predict the overall stability of the structure, the interaction between the components of the structure in providing restraint against instability of individual members, and the local stability of each individual member. Development of such theories and corresponding algorithms require a thorough investigation. The aim of this paper is to investigate the instability of single columns without large deflections by means of the second order structural theory and to study the influence of imperfections on the behaviour of such structural elements

    GEOMETRICAL TERMINOLOGY AS APPLIED TO UMBRELLA SURFACES

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    В статье приведены определения зонтичных поверхностей, поверхностей зонтичного типа, волнообразных, волнистых и рифленых поверхностей

    Safety assessment of massive buttress dams in the presence of thermal cracks in them

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    In the 1950s, the construction of hydropower facilities began in the regions of Siberia and the Far East, characterized by harsh climatic conditions, which should be taking into account to predict the stress state of dams. The aim of the study is an assessment of the conditions for the formation of temperature cracks in concrete dams and their influence on the further operation of the structure, as well as measures and technologies to combat cracking in massive concrete. Thermal stresses often exceed the stresses caused by the action of external loads and lead to the appearance of cracks in the concrete. Almost all modern concrete dams are subject to thermal cracking today. Appropriate design and technological measures must be provided for. When studying the thermally stressed state of lightweight concrete dams, the method of direct reproduction of thermal deformations on models made of brittle materials and computational methods oriented towards computer methods of solving problems are used. The results of modeling and computational studies of massive buttress dams are presented and the influence of the main influencing factors is considered, taking into account the effect of cracking on the operation of such dams

    Method of computational models of resistance for reinforced concrete

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    Based on a comprehensive analysis of the experimental studies from the standpoint of their convergence with the theoretical solutions, the computational models of resistance (CMR) of reinforced concrete are proposed. These models include CMR1 - modeling of normal cracks, CMR2 - modeling of inclined cracks, CMR3 - modeling of diagonal cracks, CMR4 - modeling of intersecting cracks in the wall, CMR4* - modeling of cracks in a flat slab, and CMR5 - modeling of spatial cracks in torsion with bending, CMR5* - modeling of spatial cracks in bending with transverse force. Also, a hierarchy of computational models of the second and third levels is proposed. The distribution of intensity of working reinforcement along the cross-section of the calculated element was obtained in an analytical form by creating closed equations of blocks, corresponding to the blocks of the reinforced concrete element under the condition of equality to zero of partial derivatives of the Lagrange function to determine the maximum crack opening width. It is considered the effect proposed by the author on the additional deformation impact of the reaction “concrete - reinforcement” from the discontinuity of concrete during the formation of the crack by means of a special model of the two-cantilever element of fracture mechanics. Hypotheses about the distribution of linear and angular deformations during cross-section with account of gradients of deformations caused by formation of cracks were formulated for a complex-stressed element subjected to torsion with bending. Crack opening is defined as mutual displacements of reinforcement and concrete, taking into account deformation. The consolidation of substructures in the building system is performed by the method of initial parameters
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