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Opis: The topic of this paper is a novel evaluation of the integral representation of the surface Greenćs function for a layered half-space, loaded on its surface by a harmonic tangential point force. The equations of motions are reduced to wave equations by the introduction of wave potentials. The Hankel transform is applied to them and they are consecutively solved leading to the integral representation of surface displacements. They are consecutively evaluated by the proposed three step procedure. First the singularity is extracted. It is further noted that so obtained integrals, after suitably chosen branch cuts and analytic continuation of integrands are introduced, can be evaluated by contour integration for an arbitrary number of layers. They are, therefore, expressed by number of residues at the poles of integrand and the integrals along finite portions of the branch cuts. The latter ones can easily be evaluated to any desired accuracy leading to a closed form solution. Some numerical results corroborating the presented approach are given.
Ključne besede: elastodynamics, elastic wave propagation, Green`s function, horizontaly layered half-space, horizontal point load
Objavljeno v DKUM: 05.06.2018; Ogledov: 1407; Prenosov: 86
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Opis: The Green's function in surface displacement plays an important role in soil structure interaction. In evaluating the Green's function, several difficulties occur because it is formulated in the infinite integral form. This paper outlines a method of analyzing the steady-state dynamic response of an elastic layer subjected to general point load excitation. It is assumed that the load is applied at the surface. The application Hankel integral transform, to the governing differential equations and boundary conditions yields the response displacements at the surface in integral representation. It will be shown that these semi-infinite integrals can be reduced to the integral with the finite range of integration, which can be efficiently taken numerically. The numerical results are presented, which show the efficiency of the developed procedure.
Ključne besede: civil engineering, geomechanics, soil-structure interaction, layered halfspace, Green's function, elastodynamics
Objavljeno v DKUM: 15.05.2018; Ogledov: 1665; Prenosov: 98
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Opis: The paper covers the derivation of a new finite element for beams with transverse cracks. The derivation is based on a simplified computational model that has already proved itself suitable for the inverse identification of cracks. The model embodies all the necessary major information about the structure's response from the inverse identification point of view, where the presence and location and, if possible, the depth of the crack should be detected from the measured response, usually dynamic. In such situations the stress distributions obtained from 2D finite elements analysis are not as important as the computational model being capable of reliably describing the displacement of the structure. However, from numerical studies it also became evident that the relevance of the model decreases with element thickness. This indicated that shear forces should be included in the analysis process. Therefore, derivation of a new finite element with the inclusion of shear forces effect has been executed. The stiffness matrix for transversely cracked slender beams, as well as the derivation of interpolation functions is presented and all expressions are given in symbolic forms. The example shows that, although with significantly less computational effort than with 2D FE meshes, significant improvement in transverse displacements can be obtained with the presented beam finite element.
Ključne besede: beams, transverse cracks, computational model, finite element method, transverse displacements
Objavljeno v DKUM: 01.06.2012; Ogledov: 2431; Prenosov: 111
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Opis: The topic of this paper is to show that the integrals of infinite extent representing the surface displacements of a layered half-space loaded by a harmonic, vertical point load can be reduced to integrals with finite integration range. The displacements are first expressed through wave potentials and the Hankel integral transform in the radial coordinate is applied to the governing equations and boundary conditions, leading to the solutions in the transformed domain. After the application of the inverse Hankel transform it is shown that the inversion integrands are symmetric/antimetric in the transformation parameter and that this characteristic is preserved for any number of layers. Based on this fact the infinite inversion integrals are reduced to integrals with finite range by choosing the suitable representation of the Bessel function and use of the fundamental rules of contour integration, permitting simpler analytical or numerical evaluation. A numerical example is presented and the results are compared to those obtained by the CLASSI program.
Ključne besede: civil engineering, soil mechanics, Green`s function, layered half-space, vertical point load
Objavljeno v DKUM: 31.05.2012; Ogledov: 2472; Prenosov: 42
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Opis: Diplomsko delo obravnava zakonodajne okvire na področju učinkovite rabe energije v stavbah in pristope k preračunu energetske učinkovitosti ovoja stavb s pomočjo računalniških programskih orodij. Predstavili smo ureditev zakonodaje za področje URE, s poudarkom na direktivi EPBD ter pravilniku PURES. Predstavili smo pristope k računanju energetske učinkovitosti ovoja stavb in podrobneje analizirali program ECOTECT. V programu smo uvozili 2D načrte, naredili 3D model objekta ter izvedli preračun toplotnih karakteristik. Na enostavnejšem modelu smo primerjali rezultate programa ECOTECT s programom URSA, kateri je po metodologiji preračuna skladen s pravilnikom PURES.
Ključne besede: učinkovita raba energije (URE), obnovljivi viri energije (OVE), direktiva EPBD, modeliranje objekta, energetska analiza objekta
Objavljeno v DKUM: 09.12.2010; Ogledov: 3478; Prenosov: 388
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