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  • On the issue of calculating the reinforcement in the junction of a beamless monolithic plate with a column

    The article discusses the results of the calculation of reinforcement in monolithic reinforced concrete floors. The subject of the study is the reinforcement of the slab section located next to the column. The study was carried out by setting up a computational experiment. Modeling was performed in software systems: Revit, Sapphire and Lira-CAD. Finite element models were calculated in Lira-CAD software. A total of 7 series of samples were calculated. The samples are a fragment of a monolithic reinforced concrete floor of a civil building. Investigated factors: triangulation parameters; the presence or absence of absolutely rigid bodies in the node. The authors performed a comparative analysis of the results of a computational experiment. It was found that for the most correct and economical selection of reinforcement in models without the use of AFL, it is desirable to take the triangulation step in the slab equal to the side of the column section or more than this value by no more than 15%, since an increase in the size of the finite elements leads to an underestimation of the reference moment and the resulting area calculation longitudinal working reinforcement. With this approach, the value of the maximum moment, and, therefore, the area obtained by the calculation of the reinforcement will be 6% higher, which makes it more preferable, although it increases the complexity of creating a finite element circuit.

    Keywords: BIM technology, reinforced concrete, girder-free overlap, reinforcement, triangulation, finite element, reinforcement selection, computational experiment, Rewit, Sapphire, Lira-CAD

  • Features of using BIM technology in the calculation of reinforced concrete structures

    The article discusses the results of the calculation of monolithic non-slab floors. The authors used software that supports BIM design technology. Models were created in Rewit Sapphire and Lyra-SAPR. The article describes the method of creating computer models. The computational experiment plan and the main parameters of the calculated prototypes are given. A total of four series of samples was calculated. The series differ in the way they create a computer model. In each series, all methods of triangulation that are available for this software package are implemented. To ensure the comparability of results, the step of triangulation in each of the series was taken to be the same: 0.17, 024, 0.4, 0.46, 0.55, 0.67 and 0.86 m. The authors made a comparative analysis of the quality of computer models after they were imported into the PC Lira-SAPR. It has been established that errors are observed when importing schemes from different software systems. Characteristics of the material, the stiffness of the elements and the load are not always transmitted correctly. This circumstance forces to do additional work. Namely, a detailed check of the circuit and its adjustment manually. BIM technology, reinforced concrete, girder-free overlap, reinforcement, triangulation, finite element, reinforcement selection, computational experiment, Rewit, Sapphire, Lira-CAD.

    Keywords: BIM technology, reinforced concrete, girder-free overlap, reinforcement, triangulation, finite element, reinforcement selection, computational experiment, Rewit, Sapphire, Lira-CAD

  • Analysis of methods of calculation of girderless floors on breakdown

    In article results of the analysis of method of calculation of flat plates of girderless floors are considered on breakdown according to the Russian and foreign design codes are considered. The analysis of the received results demonstrates that in the considered calculation procedures on breakdown similar settlement models are used and identical power factors are considered. Namely the pressing-through effort and the bending moments operating in two planes. Taking note of the moments in various techniques is carried out in two ways. The first way – tangent tension is entered into settlement model. And each technique offers the form of an epyura of tangent tension. The second way – introduction to a condition of durability of the empirical coefficient considering influence of the bending moments. Approach to purpose of geometrical parameters of a settlement (critical) contour is not identical. Contours of different techniques differ in a form and the sizes. And the difference of the sizes is very considerable. It is established that work of knot of interface of girderless flag with a column is studied yet not fully and additional researches on generalization of calculation procedures are required.

    Keywords: reinforced concrete, girderless floor, breakdown, working height of section, transversal armature, pyramid of breakdown

  • Investigation of the influence of the deviations of the position of the working armature from the project on the bearing strength of the overlap

    In the article results of the analysis of analytical dependences and results of the computing experiment executed in Lyr-CAD environment are considered. The purpose of the performed work is a quantitative assessment of the reduction in strength of beams of monolithic reinforced concrete overlappings caused by errors made during the performance of reinforcement work. In particular, an increase in the thickness of the protective layer of concrete and the consequent reduction in the working height of the section are considered. The data analyzed for both reference and span cross sections are analyzed. In total, four series of samples were selected, differing in the class of concrete (B15, B20, B25 and B30). Each series consisted of 9 samples having different working height sections in the reference and span sections. The working height of the section varied from 5 to 22%. The finite element model was created in the LIRA-CAD environment. In the course of the analysis, the effect of changing the working height of the section on the area of ​​the reference and passing reinforcement, selected for strength, was investigated.

    Keywords: It is established that the degree of influence of the deviations of the position of the reinforcement from the design in the reference sections and in the span is different. The greatest danger is represented by the support sections, that is, the overlapp

  • Investigation of the effect of the ratio of the rigidity of the structural system to the dynamic parameters of a multi-storey building depending on the seismicity of the platform

    The results of a computational experiment performed in the Lira-SAPR environment are considered in the article. The purpose of the experiment is modal analysis of various structural schemes of multi-storey reinforced concrete frame under pulsating and seismic influences. The considered design schemes differ in the ratio of the frame and diaphragm components of the frame. It was calculated three series of samples, differing by the ratio of rigidity. The stiffness ratio varied from 20% to 65.9%. Within each series calculations were performed for seismicity of 7, 8 and 9 points. For each variant of seismicity, the soils of the 1st, 2nd and 3rd seismicity categories were considered. It is established that when the role of the frame part increases, the distribution of the modal masses shifts towards the lower forms of oscillations, and the numerical values of their frequencies decrease. Accelerations of the nodes of the coating from the ratio of rigidity do not depend. They increase with increasing seismicity of the site. The ratio of stiffness affects the total consumption of the reinforcement of slabs. This influence is significant in the range of values of the ratio from 20.5% to 42.5%. Further increase in the ratio of stiffness to the consumption of reinforcement influences slightly.

    Keywords: seismicity, category of soils by seismic properties, modal analysis, rigidity, selection of fittings, PC Lira-SAPR

  • Research of influence of parameters of triangulation in the environment of the programmatic complex SAPPHIRE on the results of calculation.

    Modern programmatic complexes, supporting BIM technologies, allow in the automatic mode to carry out a transition from the 3d-модели of building to the model analytical, and then to the calculation certainly to the element model of building, the calculation of that is conducted with the use of programmatic complexes being based on the use of method of eventual elements. The results of calculation of different variants of the net of eventual elements, generated by facilities of the programmatic complex SAPPHIRE, are considered in the article. As a model for a calculable experiment the fragment of monolithic multistory girderless framework is accepted. The knot of leaning of flag on a column was designed both with the use of absolutely hard body and without him. The step of triangulation was varied in limits a from 1/35 to 1/5 span. The article of analysis is choose the area of lower longitudinal armature along the axis "Х" in the middle of flight. It is set that not dependency upon a type and step of triangulation the use of absolutely hard bodies conduces to the decline of the armature required by a calculation on the average it is Also certain on 6 %., that type and step the triangulations used in the programmatic complex SAPPHIRE substantial influence on the result of selection of flight armature do not render. However it is necessary to take into account that this result is got for charts in that obligatory is eventual elements, the centres of gravity of that are situated in the middle of flight, to what it is needed to aim in the process of creation of computer model of building.


  • To the question of reinforcement bezbalochnyh floors using PC SAPPHIRE

    In the article the results of reinforcement of monolithic reinforced concrete slab bezbalochnyh, different parameters of a finite element mesh, under other equal characteristics. Of course cell model was created by means of PC SAPPHIRE with subsequent transfer of analytical model in LIRA-CAD when creating analytical models used three variants of triangulation, namely: rectangular, triangular and adaptive step triangulation ranged over a wide range-from 1/6 up to 1/30 span. Bearing slabs at columns was carried out on two variants : using an absolutely rigid body and without it. The subject analysis of selected area of the upper longitudinal bearing fittings. During the analysis process was investigated the influence of automatic finite element mesh triangulation on anchor square fittings. Found that in all cases an increase in triangulation step reduces the required for calculating the square top of the longitudinal reinforcement. This reduction may reach 85%, and in case of insufficient quality control finite element mesh is going to cause a serious error in the calculation. When automatically generating a mesh leaf size can significantly exceed step triangulation. All meshes with the zone of transition from AGT to the plate in the form of triangles effect is observed the increase required for calculating reinforcement as you go further away from the brink of columns, that in our view it is illogical. Practical value as the most simple way, has the option of split slabs into rectangular finite elements with a size equal to or slightly greater than the section of the column. without the use of absolute hard bodies.

    Keywords: monolithic frame, non-beam overlapping, triangulation, selection of reinforcement, design calculation, PC SAPPHIRE, PC LIRA-CAD

  • Analysis of influence of parameters of net of eventual elements on the results of selection of longitudinal armature in a monolithic girderless floor

    The results of numeral experiment you show that to split beamless slabs on finite elements without the use of absolutely rigid bodies true the following statement: with the increase of the size of the finite element area is required for calculating the reference valve As.2 is reduced. In all considered grids with the area of the transition from AЖТ to the plate in the form of triangles observed the effect of the increase required for the calculation of rebar on the distance from the face of the column, which in our opinion is illogical and difficult to explain. The creation of transition zones with finite elements having dimensions close to the size of the AЖТ leads to low results and can not be considered a good solution. The transition from AЖТ to the plate with a crushing grid to a size equal to half of the column cross-section gives results almost identical with the variant of splitting the plate into finite elements of size equal to the cross section of the column without the use of absolute rigid bodies. Given the complexity of the representation of junctions of columns with plate type 3хАЖТ practical importance is a variant of the partitioning plates (in the node pair with the column) on a square (close to square) finite elements, whose dimensions are equal to the cross section of the column.

    Keywords: reinforced concrete slab, monolithic structure, the calculation of structures in Lira-SAPR