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Effect of structure–ground interaction on shrinkage stresses in foundation reinforced concrete elements

Grosel Jacek, Pakos Wojciech

Studia Geotechnica et Mechanica

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2025

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Vol. 47, nr 2

121--133

EN

This paper presents a numerical analysis of the shrinkage of reinforced concrete foundations on the ground, known as mat foundations. It presents Finite Element Method (FEM) calculations of a beam and its verification with analytical solutions. Two numerical models of mat foundations have been adopted for the purpose of this study. The first model is a foundation resting directly on the ground, that is, on an elastic Winkler base. The second numerical model consists of layers, that is, a mat foundation and a substructure (lean concrete), taking into account the frictional forces between these layers. The Mohr–Coulomb model was used in the analyses. Conclusions were drawn from the numerical analyses on the influence of the soil substrate on the magnitude of the shrinkage stresses. Modelling the interaction between the foundation and a concrete sole using elastic bonds is clearly suboptimal. Using friction to model this connection is a better approach as it avoids underestimating shrinkage stresses. The differences can be up to an order of magnitude.

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Badanie wpływu pracy maszyn na drgania konstrukcji wsporczej w hali produkcyjno-magazynowej

Grosel Jacek, Pakos Wojciech

Przegląd Budowlany

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2025

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R. 96, nr 5

38--42

PL

W artykule przedstawiono wyniki analizy dynamicznej konstrukcji wsporczej, której nadmierne drgania wywoływane są pracą maszyn. Wykonano pomiary drgań w różnych punktach konstrukcji przy zróżnicowanych parametrach pracy. Analiza wyników wykazała, że głównym źródłem drgań są wstrząsacze pracujące z f ≈ 25 Hz. Stwierdzono, że drgania w kierunku pionowym są około 8 razy większe niż w kierunkach poziomych. Drgania pomostów były około 4,6 razy wyższe niż drgania konstrukcji stalowej. Konieczne jest dalsze monitorowanie, a także modernizacja systemu monitorującego proces produkcyjny.

EN

This paper presents the results of a dynamic analysis of a support structure. The analysis was performed to identify excessive vibrations caused by the operation of machinery. Vibration measurements were taken at different points of the structure with different operating parameters. Analysis of the results showed that the main source of vibration is the shakers operating at f ≈ 25 Hz. Vibrations in the vertical direction were about 8 times higher than in the horizontal directions. The vibration of the platforms was about 4,6 times higher than the vibration of the steel structure. It is essential to continue monitoring and upgrade the system that monitors the production process.

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Theoretical and numerical modeling of a shallow foundation stiffness based on the theory of elastic half-space

Pakos Wojciech, Helowicz Andrzej

Studia Geotechnica et Mechanica

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2024

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Vol. 46, nr 4

302--317

EN

The paper presents the derivation of equations for the calculation of the spring constants ky, kz, and kϕ and the spring coefficients βy, βz, and βϕ used in the modeling of a foundation with a rectangular base on elastic soil. All the equations were derived based on information provided in literature, for example, Barkan, Gorbunov-Possadov, and Whitman et al. To demonstrate the application of these equations in practice, two numerical models of a reinforced concrete frame structure that was built on soil were created using Abaqus FEA software. Model A represents a complex three-dimensional numerical model that consists of a reinforced concrete frame structure, which has a soil layer beneath it. Model B represents a simple three-dimensional numerical model consisting of a reinforced concrete frame structure, where the stiffness of the soil layer beneath the structure was modeled with vertical, horizontal, and rocking spring constants applied to the bottom of each foundation. Due to the nonlinear boundary condition used in the supports of the concrete frame model, such as contact and friction, all the involved loads were incorporated into a single load case, and a large displacement formulation was used in the analysis. The authors focused on the method of a simplified modeling of frame structures founded on soil. To conduct comparative analyses, two columns and two beams from each model were selected, from which the internal forces and displacements were compared. The findings of the comparative analysis are presented in tables and then discussed.