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Assessment of Pullout Stiffness of Grillage Foundations in Lattice Tower Structures
Traditionally and based on the common design codes, the foundation of lattice tower structures has been considered as a fixed base, regarding no soil–structure interaction or foundation flexibility. As the lattice tower structures are subjected to complex dynamic loads and also specific nonlinear behavior, the foundation performance and consequently overall tower response under static and dynamic loads are dependent on the stiffness and damping characteristics of the foundation. To predict the foundation rigidity in different directions in numerical modeling methods, the analytical equations have been suggested in the literature in the form of impedance functions. However, the relations are generally for concrete foundations and more importantly do not include the pullout stiffness. In this study, experimental pullout tests of grillage foundations, performed by Hydro-Québec, in three different soil types including sand, clay and crushed gravel have been investigated to calculate and predict the pullout stiffness of soil-foundation system in each soil type. Exploring theoretical expressions in calculating pullout resistance of grillage foundations and tests results, the closer results to experimental values were presented. Developing a numerical code, a curve fitting has been performed for all tests of the same soil type to reproduce the normalized force–displacement curves, representing elastic, elastoplastic and plastic behaviors of the soil-foundation system under tension forces. The results are normalized load–displacement curves, suggesting three normalized stiffnesses and two normalized displacements for clay (cohesive soils), sand and crushed gravel (non-cohesive soils) which could be implemented in prediction of the foundation pullout rigidity with an arbitrary geometry and depth of embedment. The normalized curves are compared to available analogous results in the literature.
Assessment of Pullout Stiffness of Grillage Foundations in Lattice Tower Structures
Traditionally and based on the common design codes, the foundation of lattice tower structures has been considered as a fixed base, regarding no soil–structure interaction or foundation flexibility. As the lattice tower structures are subjected to complex dynamic loads and also specific nonlinear behavior, the foundation performance and consequently overall tower response under static and dynamic loads are dependent on the stiffness and damping characteristics of the foundation. To predict the foundation rigidity in different directions in numerical modeling methods, the analytical equations have been suggested in the literature in the form of impedance functions. However, the relations are generally for concrete foundations and more importantly do not include the pullout stiffness. In this study, experimental pullout tests of grillage foundations, performed by Hydro-Québec, in three different soil types including sand, clay and crushed gravel have been investigated to calculate and predict the pullout stiffness of soil-foundation system in each soil type. Exploring theoretical expressions in calculating pullout resistance of grillage foundations and tests results, the closer results to experimental values were presented. Developing a numerical code, a curve fitting has been performed for all tests of the same soil type to reproduce the normalized force–displacement curves, representing elastic, elastoplastic and plastic behaviors of the soil-foundation system under tension forces. The results are normalized load–displacement curves, suggesting three normalized stiffnesses and two normalized displacements for clay (cohesive soils), sand and crushed gravel (non-cohesive soils) which could be implemented in prediction of the foundation pullout rigidity with an arbitrary geometry and depth of embedment. The normalized curves are compared to available analogous results in the literature.
Assessment of Pullout Stiffness of Grillage Foundations in Lattice Tower Structures
Lecture Notes in Civil Engineering
Gupta, Rishi (editor) / Sun, Min (editor) / Brzev, Svetlana (editor) / Alam, M. Shahria (editor) / Ng, Kelvin Tsun Wai (editor) / Li, Jianbing (editor) / El Damatty, Ashraf (editor) / Lim, Clark (editor) / Bahari, Majid (author) / Langlois, Sébastien (author)
Canadian Society of Civil Engineering Annual Conference ; 2022 ; Whistler, BC, BC, Canada
Proceedings of the Canadian Society of Civil Engineering Annual Conference 2022 ; Chapter: 73 ; 1073-1090
2023-08-06
18 pages
Article/Chapter (Book)
Electronic Resource
English
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