An improved analytical model based on rheological-dynamical analogy (RDA) is briefly explained and used for the analysis of concrete cylinders under compression. The approach involves standard mechanical properties such as compressive strength, elastic modulus, concrete density and Poisson's ratio for the prediction of both the ascending and the descending branch of the stress-strain curve. Our own experimental data for arbitrarily selected high strength concrete with high deformability was analyzed. Further, the validity of the RDA model is checked against tests of other authors for one normal concrete and for six recycled aggregate concrete mixtures. To demonstrate the capabilities of the improved model, using analytically established stress-strain relations for analyzed samples, the moment-curvature relations and ductility of reinforced concrete beams in bending were numerically examined. The analysis showed that the ductile behavior of beams made of concrete with recycled aggregate can be achieved by limiting the reinforcement ratio to 0.01 if the recycled concrete aggregate is used and to 0.02 for recycled brick aggregate.
There is a great deal of RCFPS for which both the geometry and the material properties can be considered as constants along a main direction, straight or curved, while, generally, only the loading distribution may vary (e.g. thin-walled beams, cylindrical and prismatic shell roofs [2] and box-girder bridges [3,4]). In many cases, the performance of these structures is also improved by means of proper longitudinal prestressing systems. For these structures, the design process should lead to define the optimal morphology of the transversal cross-section, which means its geometry, size, shape and topology, as well as the layout of the prestressing system, described by the prestressing forces and the cables profile.In such context, the attention of this paper is focused on the optimal design of RCFPS composed by flat plates and subjected to multiple loading conditions, Fig. 1 (a). A proper modeling of these structures can be found within the framework of the FSM. As well known, this method is based on the formulation of a special class of finite elements that are as long as the structure and interconnected along the nodal lines that constitute the sides of the strips themselves. The FSM was originally developed by Cheung [1]. The well known uncoupled formulation, represents a semi-analytical finite element method (FEM). As far as linear analysis is concerned, it takes advantage of the orthogonality properties of harmonic functions in the stiffness matrix formulation.However, in the case of the geometric nonlinear analysis, the integral expressions contain the products of trigonometric functions with higher-order exponents, and therefore the orthogonality characteristics are no longer valid. All harmonics are coupled, and the stiffness-matrix order and bandwidth are pro-
Резиме: У раду су приказани и коментарисани прорачунски дијаграми напондилатација за бетон и арматуру према Еврокоду 2 и упоређени са одговарајућим дијаграмима према ПБАБ'87. Указано је на новине које доноси примена билинеарног радног дијаграма за челик без ограничења дилатација. Дискутована је потреба усвајања граничних величина дилатација у арматури. Коментарисан је "додатни коефицијент сигурности" за бетон, усвојен у Националном прилогу, те анализиран његов утицај на потребну површину арматуре и прорачунску носивост пресека. На примеру правоугаоног армиранобетонског пресека изложеног чистом правом савијању упоређени су резултати добијени према Еврокоду 2, применом оба радна дијаграма за челик, међусобно и са резултатима према ПБАБ'87.
Summary:The paper presents and comments stress-strain diagrams of concrete and reinforcement according to Eurocode 2 and compares them to the corresponding diagrams of PBAB'87. It points to the changes brought about by the application of bilinear working diagram for steel without strain limitation. The necessity of adopting the steel strain limits is discussed. The "additional safety factor" for concrete, which was adopted by the National Annex, is commented, and its influence to the required cross sectional area of reinforcement and design value of section resistance analysed. On the example of rectangular reinforced concrete cross-section in pure bending, the results obtained to Eurocode 2, using both working diagrams for steel, are compared mutually and with the results according to PBAB'87.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.