Abstract
In the scope of this master thesis, the subgrade reaction stiffness of shallow and pile foundations for bridge pillars is examined. The results of these studies are compared with common methods for the determination of the subgrade reaction modulus.
In the first part, shallow foundations are examined by considering rotatory, translational and combined load cases. The numerical analyses are performed with the finite element program PLAXIS 2D AE.02. With the stresses and deformations, which are ascertained in the numerical studies, the particular spring stiffness is calculated. The calculation of the spring stiffness is according to the subgrade reaction modulus method. Afterwards, this stiffness is compared in terms of head displacements of the pillars with results of common methods for determining the subgrade reaction modulus. These comparisons are leading to considerable discrepancies in some cases. Furthermore, nomograms are proposed as possible calculation remedies.
The second part deals with the determination of the horizontal subgrade reaction modulus of pile foundations for bridge pillars. The studies cover single piles as well as pile groups that are arranged in one and two rows. The execution of the numerical analyses for the pile foundations are performed by using PLAXIS 3D 2013.01. The evaluations of the studies are compared with the results of the approach according to DIN 1054 for determination of horizontal subgrade reaction modulus of piles. The outcome of the comparisons shows that DIN 1054 gives a good method to determine the design moment of the piles. Due to the fact that the method following DIN 1054 does not consider the applied load, it is only limitedly possible to calculate the deformations of the overall system.
In the first part, shallow foundations are examined by considering rotatory, translational and combined load cases. The numerical analyses are performed with the finite element program PLAXIS 2D AE.02. With the stresses and deformations, which are ascertained in the numerical studies, the particular spring stiffness is calculated. The calculation of the spring stiffness is according to the subgrade reaction modulus method. Afterwards, this stiffness is compared in terms of head displacements of the pillars with results of common methods for determining the subgrade reaction modulus. These comparisons are leading to considerable discrepancies in some cases. Furthermore, nomograms are proposed as possible calculation remedies.
The second part deals with the determination of the horizontal subgrade reaction modulus of pile foundations for bridge pillars. The studies cover single piles as well as pile groups that are arranged in one and two rows. The execution of the numerical analyses for the pile foundations are performed by using PLAXIS 3D 2013.01. The evaluations of the studies are compared with the results of the approach according to DIN 1054 for determination of horizontal subgrade reaction modulus of piles. The outcome of the comparisons shows that DIN 1054 gives a good method to determine the design moment of the piles. Due to the fact that the method following DIN 1054 does not consider the applied load, it is only limitedly possible to calculate the deformations of the overall system.
Translated title of the contribution | Numerical studies on subgrade reaction stiffness of shallow and pile foundations of bridge pillars |
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Original language | German |
Publication status | Published - 2015 |
Keywords
- subgrade reaction stiffness
- spring stiffness
- subgrade reaction modulus
- Soil-Structure-Interaction
ASJC Scopus subject areas
- Building and Construction
- Civil and Structural Engineering
Fields of Expertise
- Sustainable Systems