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T.J. van der Wel
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2 records found
1
Master thesis
(2018)
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Thijs van der Wel, Sebastiaan N. Jonkman, Peter Quist, Timo Schweckendiek, Alfred Roubos, Dirk-Jan Jaspers Focks
Uncertainties in the soil parameters play a major role in the design of quay walls. In the current design approach, partial factors are prescribed to account for uncertainties in the soil, as well as for other types of uncertainties. This semi-probabilistic (level I) design approach needs to result in a reliable design for a range of quay structures and for multiple soil stratifications. It is therefore expected that, in general, this method results in overdimensioning of the structure. Whether this assumption holds, is investigated in this thesis by carrying out a reliability analysis for two quay walls in the Port of Rotterdam. The first case study covers a simple double-anchored combi-wall, whereas in the second case study a quay wall with relieving platform is considered.
Only the most relevant failure mechanisms were considered, which are yielding of the combi-wall, yielding of the anchor bar, shear failure of the grout body and soil mechanical failure. These failure mechanisms are complex soil-structure interaction problems. Therefore, both the soil and the quay structure have been modelled with the finite element program Plaxis 2D, using the Hardening soil model. For performing the probabilistic calculations on this model, the probabilistic module ProbAna has been used. This is a package developed by Plaxis which couples several types of reliability methods to the finite element software of Plaxis 2D. As the computational effort is relatively large when using FEM, the First Order Reliability Method (FORM) was used over sampling methods like Directional Sampling and Crude Monte Carlo simulation.
The results for the simple quay wall showed that the reliability level was sufficient for all considered limit states. Hence, almost all partial factors derived on this quay wall were lower than currently prescribed by the Eurocode. In the second case study, a quay wall with relieving platform, monitoring data of multiple years was used for calibration of the Plaxis-model. Thereafter, the reliability for the limit states yielding of the wall and soil mechanical failure was evaluated. It turned out that for both limit states, the reliability index was too low compared to the target reliability.
Although each case study concerned a different type of quay wall, the results reveal that choices made in the design, either optimistic or pessimistic, can have large influence on the reliability. Perhaps just as important, are the assumptions made regarding the stochastic description of the soil. It is still under discussion up to what distance soil parameters are correlated in space and how spatial averaging should be applied. Reference calculations showed that choices regarding the amount of independent soil layers and the degree of spatial averaging have a large influence on the reliability. More fundamental research to these topics is therefore recommended.
...
Only the most relevant failure mechanisms were considered, which are yielding of the combi-wall, yielding of the anchor bar, shear failure of the grout body and soil mechanical failure. These failure mechanisms are complex soil-structure interaction problems. Therefore, both the soil and the quay structure have been modelled with the finite element program Plaxis 2D, using the Hardening soil model. For performing the probabilistic calculations on this model, the probabilistic module ProbAna has been used. This is a package developed by Plaxis which couples several types of reliability methods to the finite element software of Plaxis 2D. As the computational effort is relatively large when using FEM, the First Order Reliability Method (FORM) was used over sampling methods like Directional Sampling and Crude Monte Carlo simulation.
The results for the simple quay wall showed that the reliability level was sufficient for all considered limit states. Hence, almost all partial factors derived on this quay wall were lower than currently prescribed by the Eurocode. In the second case study, a quay wall with relieving platform, monitoring data of multiple years was used for calibration of the Plaxis-model. Thereafter, the reliability for the limit states yielding of the wall and soil mechanical failure was evaluated. It turned out that for both limit states, the reliability index was too low compared to the target reliability.
Although each case study concerned a different type of quay wall, the results reveal that choices made in the design, either optimistic or pessimistic, can have large influence on the reliability. Perhaps just as important, are the assumptions made regarding the stochastic description of the soil. It is still under discussion up to what distance soil parameters are correlated in space and how spatial averaging should be applied. Reference calculations showed that choices regarding the amount of independent soil layers and the degree of spatial averaging have a large influence on the reliability. More fundamental research to these topics is therefore recommended.
...
Uncertainties in the soil parameters play a major role in the design of quay walls. In the current design approach, partial factors are prescribed to account for uncertainties in the soil, as well as for other types of uncertainties. This semi-probabilistic (level I) design approach needs to result in a reliable design for a range of quay structures and for multiple soil stratifications. It is therefore expected that, in general, this method results in overdimensioning of the structure. Whether this assumption holds, is investigated in this thesis by carrying out a reliability analysis for two quay walls in the Port of Rotterdam. The first case study covers a simple double-anchored combi-wall, whereas in the second case study a quay wall with relieving platform is considered.
Only the most relevant failure mechanisms were considered, which are yielding of the combi-wall, yielding of the anchor bar, shear failure of the grout body and soil mechanical failure. These failure mechanisms are complex soil-structure interaction problems. Therefore, both the soil and the quay structure have been modelled with the finite element program Plaxis 2D, using the Hardening soil model. For performing the probabilistic calculations on this model, the probabilistic module ProbAna has been used. This is a package developed by Plaxis which couples several types of reliability methods to the finite element software of Plaxis 2D. As the computational effort is relatively large when using FEM, the First Order Reliability Method (FORM) was used over sampling methods like Directional Sampling and Crude Monte Carlo simulation.
The results for the simple quay wall showed that the reliability level was sufficient for all considered limit states. Hence, almost all partial factors derived on this quay wall were lower than currently prescribed by the Eurocode. In the second case study, a quay wall with relieving platform, monitoring data of multiple years was used for calibration of the Plaxis-model. Thereafter, the reliability for the limit states yielding of the wall and soil mechanical failure was evaluated. It turned out that for both limit states, the reliability index was too low compared to the target reliability.
Although each case study concerned a different type of quay wall, the results reveal that choices made in the design, either optimistic or pessimistic, can have large influence on the reliability. Perhaps just as important, are the assumptions made regarding the stochastic description of the soil. It is still under discussion up to what distance soil parameters are correlated in space and how spatial averaging should be applied. Reference calculations showed that choices regarding the amount of independent soil layers and the degree of spatial averaging have a large influence on the reliability. More fundamental research to these topics is therefore recommended.
Only the most relevant failure mechanisms were considered, which are yielding of the combi-wall, yielding of the anchor bar, shear failure of the grout body and soil mechanical failure. These failure mechanisms are complex soil-structure interaction problems. Therefore, both the soil and the quay structure have been modelled with the finite element program Plaxis 2D, using the Hardening soil model. For performing the probabilistic calculations on this model, the probabilistic module ProbAna has been used. This is a package developed by Plaxis which couples several types of reliability methods to the finite element software of Plaxis 2D. As the computational effort is relatively large when using FEM, the First Order Reliability Method (FORM) was used over sampling methods like Directional Sampling and Crude Monte Carlo simulation.
The results for the simple quay wall showed that the reliability level was sufficient for all considered limit states. Hence, almost all partial factors derived on this quay wall were lower than currently prescribed by the Eurocode. In the second case study, a quay wall with relieving platform, monitoring data of multiple years was used for calibration of the Plaxis-model. Thereafter, the reliability for the limit states yielding of the wall and soil mechanical failure was evaluated. It turned out that for both limit states, the reliability index was too low compared to the target reliability.
Although each case study concerned a different type of quay wall, the results reveal that choices made in the design, either optimistic or pessimistic, can have large influence on the reliability. Perhaps just as important, are the assumptions made regarding the stochastic description of the soil. It is still under discussion up to what distance soil parameters are correlated in space and how spatial averaging should be applied. Reference calculations showed that choices regarding the amount of independent soil layers and the degree of spatial averaging have a large influence on the reliability. More fundamental research to these topics is therefore recommended.
Container terminal development for the Port of Bahía Blanca
A research on the future container throughput in the Port of Bahía Blanca and the adaptation to the container terminal to these developments
Student report
(2017)
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Anniek Munters, Bas Stam, Thijs van der Wel, Robbin Wesstein, Tiedo Vellinga, Bart Wiegmans
Bahía Blanca in Buenos Aires province is located 600 kilometres south of Buenos Aires city. The port complex of Bahía Blanca has the second largest throughput in Argentina considering tons, mainly attributed to the agro – and petrochemical industry. The port handles containers as well, however with an average of 30 thousand TEU/year this throughput is rather small. The authority of the Port of Bahía Blanca sees opportunities to increase container throughput in the port due to recent developments in the region. The container throughput is estimated for 2040, considering the petrochemical cluster and fruits. Four different trends show a container throughput of respectively 30, 155, 250 and 360 thousand TEU/year. The capacity of the container terminal is estimated at 50 thousand TEU/year, based on the equipment, the dwell time and the terminal area. The terminal should improve when throughput will increase. To start, number of calls and call size are assumed based on future throughput, decreasing the average dwell time for export containers. Additionally, a larger quantity and more advanced equipment is required to handle the increase in throughput. Lastly, the terminal area itself can be increased significantly from 8ha to 22ha in its maximum configuration. The increase in storage area allows the capacity to grow from 50 thousand TEU/year to 215 thousand TEU/year. It is important to realize that further expansion of the terminal is not possible and a new location has to be considered. A multi criteria analysis in combination with a financial analysis on the possible location showed that two out of four possible new locations are suitable for the development of a new container terminal. The new container terminal should have the capacity to handle the expected container throughput generated locally. The possibility to attract additional cargo to the port was researched as well, since the Port of Bahía Blanca has an advantageous depth compared to the Port of Buenos Aires. However, on the short term it is not expected that Bahía Blanca can profit from the draught limitations in Buenos Aires since port calling cost are almost the same, Buenos Aires is located conveniently and not operating at capacity and current shipping routes are not expected to change their routes majorly.
...
Bahía Blanca in Buenos Aires province is located 600 kilometres south of Buenos Aires city. The port complex of Bahía Blanca has the second largest throughput in Argentina considering tons, mainly attributed to the agro – and petrochemical industry. The port handles containers as well, however with an average of 30 thousand TEU/year this throughput is rather small. The authority of the Port of Bahía Blanca sees opportunities to increase container throughput in the port due to recent developments in the region. The container throughput is estimated for 2040, considering the petrochemical cluster and fruits. Four different trends show a container throughput of respectively 30, 155, 250 and 360 thousand TEU/year. The capacity of the container terminal is estimated at 50 thousand TEU/year, based on the equipment, the dwell time and the terminal area. The terminal should improve when throughput will increase. To start, number of calls and call size are assumed based on future throughput, decreasing the average dwell time for export containers. Additionally, a larger quantity and more advanced equipment is required to handle the increase in throughput. Lastly, the terminal area itself can be increased significantly from 8ha to 22ha in its maximum configuration. The increase in storage area allows the capacity to grow from 50 thousand TEU/year to 215 thousand TEU/year. It is important to realize that further expansion of the terminal is not possible and a new location has to be considered. A multi criteria analysis in combination with a financial analysis on the possible location showed that two out of four possible new locations are suitable for the development of a new container terminal. The new container terminal should have the capacity to handle the expected container throughput generated locally. The possibility to attract additional cargo to the port was researched as well, since the Port of Bahía Blanca has an advantageous depth compared to the Port of Buenos Aires. However, on the short term it is not expected that Bahía Blanca can profit from the draught limitations in Buenos Aires since port calling cost are almost the same, Buenos Aires is located conveniently and not operating at capacity and current shipping routes are not expected to change their routes majorly.