Institute of Earthquake Engineering and Engineering Seismology

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    Item type:Publication,
    Development of infinite elements for simulation of unbounded media
    (Centre for Evaluation in Education and Science (CEON/CEES), 2018)
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    Demir, Aydin
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    Ozturk, Hakan
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    Item type:Publication,
    EFFECTS OF CORE STRUCTURE IN MULTIPHASE SIMULATION OF AN EARTH DAM
    (University of Zagreb Faculty of Civil Engineering, 2023-03-24)
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    Kitanovski, Toni
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    Ivanovski, Dejan
    One of the most popular themes in earthquake geotechnical engineering is the simulation considering the phase interaction among different phases inside the soil medium. The present article aims at providing numerical simulations of an earth fill dam composed of multiphase material models. Moreover, the assessment of liquefaction potential is investigated considering the presence of core structure inside the dam body which obviously has great implications for the results. The formulation of the coupled approach is presented as a mixture of three constituents – soil grains, water and air in the pores. Mixture theory is considered including the concept of volume fractions in defining of the coupled approach. An earth dam has a trapezoidal cross section with the presence of core structure inside the dam body. The flow of water is different and simulations are more time consuming for which results from literature are used in verification process. The simulation considers a nonlinear behavior with respect to the water retention curves and material model for the solid state. The hydrostatic distribution of water pressured at steady state conditions show obvious differences in saturation of the earth filled dam and are in accordance with the results from literature. The dam is assumed to be situated above a hard rock formation. The soil material of the dam body is simulated as hypoplastic material model which is nonlinear even for the small deformations. The usage of hypoplastic model and the accumulation of strain in each cycle of the stress – strain relation makes the model advantageous. Results are compared accordingly, and conclusions provide directions for further usage of the multiphase model in simulation of this type of structures
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    Item type:Publication,
    Assessment of soil behavior in seismic excitations by exploring different approaches
    (University of Zagreb Faculty of Civil Engineering, 2024-10-08)
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    Stanko, Davor
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    Salic-Makreska, Radmila
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    In geotechnical earthquake engineering seismic site response analysis is a very complex task, which has gained an increasing importance for the last decades. This paper aims to numerically simulate the effect of an earthquake input in different types of soil layers in order to get the dynamic amplification factor. The methodology for correctly simulation of seismic waves propagation includes thorough theoretical background aided with different softwares (Shake, Strata,DeepSoil and Plaxis) which allow the simulation of soil as nonlinear material model or small strain linearly elastic material. The verification of the model is done by comparison of numerical results in relation to two different soil profiles from Varazdin, Croatia and from Skopje, Macedonia. The proposed approach should demonstrate and illustrate the special points in taking into account the modelling of different layers. The earthquake input is given as acceleration signal which in case of low densities of soil material are prone to initiate higher amplifications. Finally, the advantages and limitations of the proposed numerical model are discussed in detail.
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    Item type:Publication,
    EFFECTS OF GROUND MOTION INTENSITY IN ASSESSMENT OF SOIL SLOPES IN EARTHFILL DAM
    (University of Zagreb Faculty of Civil Engineering, 2025-03-19)
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    Stanko, Davor
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    Shalic-Makreska, Radmila
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    The cumulative displacement of sloped soil masses in earth-fill dams subjected to seismic loading is fundamentally governed by both the magnitude and frequency characteristics of the seismic excitation. This correlation necessitates comprehensive numerical simulations incorporating diverse acceleration time histories to capture the full spectrum of potential seismic responses. This manuscript examines the response of an earth dam slope susceptible to seismically-induced instability under various earthquake scenarios with distinct magnitude-frequency characteristics. The accurate modeling of soil media becomes particularly critical in situations where dynamic pore pressure generation occurs within the soil matrix. The coupled numerical approach developed in this study conceptualizes the soil element as a three-phase medium composed of soil grains, pore water and pore air. The simulation considers a nonlinear behavior with respect to the water retention curves and material model for the solid state and analysis is performed by ANSYS and PLAXIS. The air pressure is assumed to stay atmospheric in the course of the calculation and matric suction is equal to a negative value of the hydrostatic stress in water pressure. The coupled model allows to take into account the deformations of the soil skeleton and simultaneously considers the pore water pressure change during the earthquake excitation. The seismic behavior of the slope gives interesting results considering both deformation and pore water pressure development. The primary objectives of this research are to investigate the seismic response of earth dam slopes under various earthquake scenarios and compare results between ANSYS and PLAXIS software implementations for multiphase soil modeling. The contributions include the development of a comprehensive coupled numerical approach that simultaneously considers soil deformation and pore pressure evolution during seismic loading along with the integration of hypoplastic material model with multiphase flow analysis.
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    Item type:Publication,
    Improving the physical and mechanical properties of clayey soil by adding waste material  fly ash and stone flour
    (Faculty of Civil Engineering and Architecture, 2025-09-11)
    Marinković, Nemanja
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    Zlatanović, Elefterija
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    Bonić, Zoran
    Stabilization of clayey soil with an inadequate physical and mechanical properties in its natural state represents one of the actual challenges in contemporary geotechnical engineering. Among numerous stabilization techniques, chemical stabilization stands out as an effective technique for stabilizing clayey soils. By applying this technique, various types of stabilizers may be used, whereby they react with soil particles and modify its structure, contributing to the permanent improvement of the physical and mechanical properties of the soil. In this study, waste materials obtained as a product of industrial processes, such as fly ash and rock flour, were considered as chemical stabilizers. A comparative analysis of the effects of adding fly ash and rock flour on improving the uniaxial compressive strength (UCS) and the shear strength parameters of clayey soil was performed, while simultaneously monitoring the durability of the achieved effects.
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    Item type:Publication,
    Harmonized methodology for cross-border hazard and risk assessment of earthquake-induced landslides at regional scale
    (Springer Science and Business Media LLC, 2025-03-25)
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    Fotopoulou, Stavroula
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    Bozzoni, Francesca
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    Item type:Publication,
    Verification of a System for Sustainable Research on Earthquake-Induced Soil Liquefaction in 1-g Environments
    (MDPI AG, 2022-09-29)
    Bojadjieva, Julijana
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    Sheshov, Vlatko
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    Edip, Kemal
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    Kitanovski, Toni
    <jats:p>Within the presented research, model tests were performed in 1-g conditions to investigate the liquefaction potential of Skopje sand as a representative soil from the Vardar River’s terraces in N. Macedonia. A series of shaking table tests were performed on a fully saturated, homogeneous model of Skopje sand in the newly designed and constructed laminar container in the Institute of Earthquake Engineering and Engineering Seismology (IZIIS), Skopje, N. Macedonia. The liquefaction depth in each shaking test was estimated based on the measured acceleration and pore water pressure as well as the frame movements of the laminar container. The surface settlement measurements indicated that the relative density increased by ~12% after each test. The observations from the tests confirmed that liquefaction was initiated along the depth at approximately the same time. The number of cycles required for liquefaction increased as the relative density increased. As the pore water pressure rose and reached the value of the effective stresses, the acceleration decreased, thus the period of the soil started to elongate. The results showed that the investigated Skopje sand was highly sensitive to void parameters and, under specific stress conditions, the liquefaction that occurred could be associated with large deformations. The presented experimental setup and soil material represent a well-proven example of a facility for continuous and sustainable research in earthquake geotechnical engineering.</jats:p>
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    Item type:Publication,
    Numerical modelling of saturated boundless media with infinite elements
    (Springer Science and Business Media LLC, 2021-02-19)
    Edip, Kemal
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    Sheshov, Vlatko
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    Wu, Wei
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    Bojadjieva, Julijana