<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Soil is an anisotropic, heterogeneous, and inelastic complex material. It is difficult to represent the exact behavior of soil by numerical modelling in practice. Conventionally, soil is simplified to an idealized model where it is considered isotropic, homogeneous, and behaves elastically under loads. The idealization, in this case, is done using the proper elastic modulus, Poisson’s ratio, and unit weight of soil depending upon the soil type. Although the exact soil behavior is simplified, using Finite Element Analysis (FEA) a more effective result can be obtained. A superstructure was modelled using ETABS using a fixed-base system and the base reaction forces were obtained. A mat and a soil element on which the mat was laid were modelled as a flexible-base system in Midas GTS NX. The base reactions obtained from ETABS were applied to the mat in the soil model to determine the settlements and, consequently, the spring stiffness. The superstructure was then modelled again, incorporating springs under the respective columns. Convergence in settlement, and base reactions were reached by iteration, and the final results from the flexible-base system were then compared with the fixed-base system. The center column settled the most, about 60 mm, and there was a decrease in settlement by 15% between the first model and the final iterated model. The base reaction for center columns decreased by 24% in the flexible base system compared to the fixed base system. However, an increase in base reaction was observed for both side and edge columns. There was an extremely erratic change in grade beams under a flexible base system, which shows that the superstructure elements are also affected by the change in the base system. It is recommended to use this approach, for the analysis of structures considering flexible base systems instead of fixed bases because it enhances the accuracy of analysis with feasible time consumption and less complex effort.</p>
</abstract>

Soil is an anisotropic, heterogeneous, and inelastic complex material. It is difficult to represent the exact behavior of soil by numerical modelling in practice. Conventionally, soil is simplified to an idealized model where it is considered isotropic, homogeneous, and behaves elastically under loads. The idealization, in this case, is done using the proper elastic modulus, Poisson’s ratio, and unit weight of soil depending upon the soil type. Although the exact soil behavior is simplified, using Finite Element Analysis (FEA) a more effective result can be obtained. A superstructure was modelled using ETABS using a fixed-base system and the base reaction forces were obtained. A mat and a soil element on which the mat was laid were modelled as a flexible-base system in Midas GTS NX. The base reactions obtained from ETABS were applied to the mat in the soil model to determine the settlements and, consequently, the spring stiffness. The superstructure was then modelled again, incorporating springs under the respective columns. Convergence in settlement, and base reactions were reached by iteration, and the final results from the flexible-base system were then compared with the fixed-base system. The center column settled the most, about 60 mm, and there was a decrease in settlement by 15% between the first model and the final iterated model. The base reaction for center columns decreased by 24% in the flexible base system compared to the fixed base system. However, an increase in base reaction was observed for both side and edge columns. There was an extremely erratic change in grade beams under a flexible base system, which shows that the superstructure elements are also affected by the change in the base system. It is recommended to use this approach, for the analysis of structures considering flexible base systems instead of fixed bases because it enhances the accuracy of analysis with feasible time consumption and less complex effort.

Behavior of Mat Foundation for a Ten-Story Building: Fixed Base vs Three-Dimensional Soil Model

Structure and Environment

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Soil is an anisotropic, heterogeneous, and inelastic complex material. It is difficult to represent the exact behavior of soil by numerical modelling in...

Behavior of Mat Foundation for a Ten-Story Building: Fixed Base vs Three-Dimensional Soil Model

Published Online: Feb 08, 2023

Page range: 153 - 160

DOI: https://doi.org/10.30540/sae-2022-017

Keywords
Elastic modulus, Poisson’s ratio, Finite Element Analysis (FEA), Midas GTS NX, settlement, spring stiffness etc

© 2022 Farhaj Hasan et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Behavior of Mat Foundation for a Ten-Story Building: Fixed Base vs Three-Dimensional Soil Model

Published Online: Feb 08, 2023

Page range: 153 - 160

DOI: https://doi.org/10.30540/sae-2022-017

KeywordsElastic modulus, Poisson’s ratio, Finite Element Analysis (FEA), Midas GTS NX, settlement, spring stiffness etc

© 2022 Farhaj Hasan et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Elastic modulus, Poisson’s ratio, Finite Element Analysis (FEA), Midas GTS NX, settlement, spring stiffness etc