Search

Reinforced concrete diaphragms are in-built supporting structures constructed directly in the ground. They are intended for reception of lateral soil pressures, and due to the thickness-height ratio they belong to the group of deformable structures. The paper presents different design methods of transversally loaded diaphragms as well as constitutive soil models which can be used on this occasion. For comparison of the described methods, one example of design of reinforced-concrete diaphragm with the analysis of obtained results was done. The diaphragm is firstly treated using classical analytical methods, and then using the numerical methods based on the concept of problem discretization using finite differences method and the STRESS, TOWER and PLAXIS software. The goal of the paper is as accurate prediction of the diaphragm and surrounding soil behavior as possible, as well as finding of the relevant impacts required for the design. [Projekat Ministarstva nauke Republike Srbije, br. TR36028: Development and improvement of methods for analyses of soil - structure interaction based on theoretical and experimental research]

The existing civil engineering standards for designing are to be replaced with a set of Eurocodes. Eurocode 7 is related to a geotechnical design, but its implementation is difficult, due to different geological, geographical and climate conditions which lead to development of different local designing traditions all over Europe. In order to overcome them, Eurocode 7 offers three design approaches and sets of partial factors to be used within. After accepting it, each country has to declare on the selection of design approach according to which designing is going to be performed and to define appropriate partial factors. This paper presents methodology for selection of appropriate design approach for spread foundations in our region where the process of introduction of Eurocodes is still active. The method based on keeping up with the similar designing procedure may also be used for other geotechnical structures.

Unlike the other eurocodes where structure designing is fairly clear, there are three design approaches offered in Eurocode 7 and sets of applied partial factors. After accepting Eurocode 7, each country has to decide on two very important decisions related to the selection of appropriate design approach according to which designing of geotechnical structures is going to be performed and define adequate partial factors. Selection of appropriate design approach is based on analyses of certain geotechnical problem both with actual and proposed methods. Therefore, it should be find out which approach is the closest to hitherto calculation 'style', which compatibility of 'old' and new method will serve as a base for selecting appropriate design approach. Moreover, it will be tested with different partial factors in order to obtain approximately the same size of structural elements or construction, which similarity will suggest the value of partial factors. Analyses and verifications are performed for such purposes for retaining walls, which conclusions, presented below, lead to solution that can be used in the region.

In this paper the possibility of using waste glass in road construction is discussed. Samples of clay material with the addition of waste glass were subjected to a series of laboratory geotechnical tests performed at the Laboratory of Geotechnics at the Faculty of Civil Engineering and Architecture in Niš. The obtained results were compared with criteria defined in the document “General technical requirements for road construction”. On this basis, the conclusions on the suitability of this mixture for the intended purpose are given. [Projekat Ministarstva nauke Republike Srbije, br. TR-36016 i br. TR-36028]

The paper presents application of nonlinear material models in the software package Ansys. The development of the model theory is presented in the paper of the mathematical modeling of material nonlinear problems in structural analysis (part I - theoretical foundations), and here is described incremental-iterative procedure for solving problems of nonlinear material used by this package and an example of modeling of spread footing by using Bilinear-kinematics and Drucker-Prager mode was given. A comparative analysis of the results obtained by these modeling and experimental research of the author was made. Occurrence of the load level that corresponds to plastic deformation was noted, development of deformations with increasing load, as well as the distribution of dilatation in the footing was observed. Comparison of calculated and measured values of reinforcement dilatation shows their very good agreement.

Geotechnical performance of 'soil-structure' systems is strongly dependent on the properties of the soil and prediction of the performance of these systems in real conditions requires accurate modeling of soil parameters. With the help of high-speed computers, now it is possible to create advanced constitutive models, but large uncertainties and variations in soil properties could reduce the advantages gained by using such models. In this paper sources and types of uncertainty in geotechnical engineering practice are first presented, followed by a review of the basic concepts and terminology of geostatistics. Finally, procedures for quantification of uncertainty and for geostatistical estimation and simulation of spatially variable soil properties are presented.

Material models describe the way they behave when loaded. The paper presents the development of the model beginning with the simplest linear-elastic and rigid-plastic ones. The basic data in the plasticity theory have been defined, such as criterion and yield (failure) surface, hardening law, plastic yield law and normality condition. Yield criteria of Tresca, Von Mises, Mohr-Coulomb and Drucker-Prager were given separately.

The paper presents a brief description of experiment within the research project 'Theoretical and experimental analysis of interaction of shallow reinforced concrete foundations and soil for the purpose of improvement of national regulations and implementaation of Eurocode system' where in situ tests of a series of reinforced concrete foundation footing were performed, by loading until failure. As a rule, methods for calculation of shallow foundations settlement on granular soils overestimate the expected settlement, and underestimate soil bearing capacity, which results in a conservative foundation design. In order to test accuracy and reliability of the different settlements prediction methods, a comparative analysis of settlements calculated using these methods and those measured during experiment, was performed.

Deflection of foundation girder supported by the deformable base has been defined by the system of differential equations, where the differential equation of the elastic line of the girder is of the fourth order. The most convenient solution of the problem is application of numerical procedures, in this case it is the finite difference method. In the paper, the mentioned method is applied in the special case of foundation girder of variable cross section loaded by arbitrary load on its ends.

In the modern civil engineering design, especially in the field of machine foundations, the dynamic actions in the form of the impulse load that is short-term, high intensity loads are very frequent. When an acting force during a short time interval remains constant, the impulse is of a rectangular form, as opposed to the trapezoid, triangular, parabolic and sinusoid form, with defined time of increase and decrease of the load. This paper considers the influence of the form of the impact impulse load on the dynamic response of the foundation structure, without changing the remaining parameters.