scholarly journals Analytical determination of the vibration frequencies and buckling loads of slender reinforced concrete towers

Author(s):  
Alexandre de M. Wahrhaftig ◽  
Marcelo A. da Silva ◽  
Reyolando M. L. R. F. Brasil
2021 ◽  
Vol 108 ◽  
pp. 45-52
Author(s):  
Jakub Holan ◽  
Radek Štefan

In the last decade, the computing power of computers has significantly increased, which enabled very detailed and accurate numerical static non-linear analyses of reinforced concrete structures to be carried out using sophisticated commercial software. However, higher risk of errors, both in the calculation inputs and algorithm, is linked with the increased detail and accuracy of numerical modelling. For this reason, it is convenient to verify the results provided by sophisticated software using simplified analytical approaches. In order to provide a tool for quick and easy verification of results provided by sophisticated software, a novel web-based application employing simplified analytical methods has been developed by the authors of this paper. This web-based application is capable of quick and easy calculations of bending moments in reinforced concrete two-way slabs. For the calculation of bending moments, the Marcus Method is employed. This method introduces a correction coefficient to the Rankine-Grashoff Theory of Equal Deflections in order to account for the torsional restraints at the corners of the slab. These analytical methods are algorithmized and implemented using the JavaScript programming language. A graphical user interface for the input of data and for the interpretation of results is created using the HTML markup language. The novel web-based application is freely available and works on all common devices and operating systems. From the presented results, it is clear that the novel web-based application is quick, easily available, user-friendly, and intuitive. The web-based application can be used for the verification of the calculated bending moments during the design of a reinforced concrete two-way slab.


Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.


2020 ◽  
Vol 50 (5) ◽  
pp. 347-350
Author(s):  
G. M. Druzhinin ◽  
N. B. Loshkarev ◽  
E. D. Solntseva ◽  
I. M. Khammatov

Sign in / Sign up

Export Citation Format

Share Document