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I.A. van der Esch
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Under harmonic excitation, soil exhibits softening behaviour that can be captured through the so-called hyperbolic soil model. The response of systems with such a material model can elegantly be obtained using the classical Harmonic Balance Method (HBM). Soil also exhibits nonlinear hysteretic damping under harmonic excitation, feature which is not incorporated in the hyperbolic soil model. The response of a system that includes also the nonlinear hysteretic damping cannot be obtained using the classical HBM. This work demonstrates the application of an advanced HBM (more specifically, alternating frequency-time HBM) for finite and infinite systems that exhibit softening behaviour and nonlinear hysteretic damping. The purpose of this model is to, in the future, investigate the influence of the nonlinear hysteretic damping on the response of such systems, as opposed to linear viscous or hysteretic damping that is usually adopted. To conclude, we show that the advanced HBM is an effective tool for revealing fundamental characteristics of continuous systems with softening behaviour and nonlinear hysteretic damping whose stationary responses consist of either standing or propagating waves.
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Under harmonic excitation, soil exhibits softening behaviour that can be captured through the so-called hyperbolic soil model. The response of systems with such a material model can elegantly be obtained using the classical Harmonic Balance Method (HBM). Soil also exhibits nonlinear hysteretic damping under harmonic excitation, feature which is not incorporated in the hyperbolic soil model. The response of a system that includes also the nonlinear hysteretic damping cannot be obtained using the classical HBM. This work demonstrates the application of an advanced HBM (more specifically, alternating frequency-time HBM) for finite and infinite systems that exhibit softening behaviour and nonlinear hysteretic damping. The purpose of this model is to, in the future, investigate the influence of the nonlinear hysteretic damping on the response of such systems, as opposed to linear viscous or hysteretic damping that is usually adopted. To conclude, we show that the advanced HBM is an effective tool for revealing fundamental characteristics of continuous systems with softening behaviour and nonlinear hysteretic damping whose stationary responses consist of either standing or propagating waves.
Soil exhibits hysteretic damping. A commonly used implementation of this type of damping are the Masing rules. They consist of a loading and an unloading branch, dened as a piecewise function and having a nonsmooth character. This paper presents a framework how steady-state solutions of the motion of a soil column, with nonlinear hysteretic damping, can be obtained by using a variant of the Harmonic Balance Method (HBM), the Alternating Frequency/Time Harmonic Balance Method (AFTHBM), applied on a discretised soil column (a lattice system). The theoretical background of the method is presented, as well as its application to a soil column with both shear strain-dependent stiness and damping. Results show that the AFTHBM is an efficient method for obtaining steady-state results for nonsmooth nonlinear behaviour, which is in this paper presented by simulations for nonlinear media. The results of the AFTHBM are sensitive to time sampling and convergence tolerances; nonetheless, if these parameters are properly chosen, the application of AFTHBM leads to good results.
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Soil exhibits hysteretic damping. A commonly used implementation of this type of damping are the Masing rules. They consist of a loading and an unloading branch, dened as a piecewise function and having a nonsmooth character. This paper presents a framework how steady-state solutions of the motion of a soil column, with nonlinear hysteretic damping, can be obtained by using a variant of the Harmonic Balance Method (HBM), the Alternating Frequency/Time Harmonic Balance Method (AFTHBM), applied on a discretised soil column (a lattice system). The theoretical background of the method is presented, as well as its application to a soil column with both shear strain-dependent stiness and damping. Results show that the AFTHBM is an efficient method for obtaining steady-state results for nonsmooth nonlinear behaviour, which is in this paper presented by simulations for nonlinear media. The results of the AFTHBM are sensitive to time sampling and convergence tolerances; nonetheless, if these parameters are properly chosen, the application of AFTHBM leads to good results.
Ciclo Sampa
A generalised bicycle network design applied to Sao Paulo
Student report
(2019)
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Anton van der Esch, Ramon Kienhuis, Chiara Ligthart, Judith Termote, Zili Wang, Robin van der Vaart, Lambert Houben
Nowadays the city of São Paulo has to deal with a lot of traffic jams. Extending the road network is no option and the public transport network cannot keep up with the capacity either. A solution must be found in another type of transport: cycling. The current bicycle infrastructure is not sufficient in terms of connectivity. In this research, a standardised bicycle network is developed for a part of the city, which can be used during future bicycle expansion projects in São Paulo. The development of the bicycle infrastructure concerns the whole city of São Paulo, resulting in a lot of interests being affected. The people behind these interests, the stakeholders, can have an influence over the project decisions, but do usually have conflicting interests. Therefore, these stakeholders are identified and analysed, through literature review and semi-structured interviews. In this case however, most stakeholders did not seem to experience any conflicts. The biggest problem in the development of the bicycle network, is that the stakeholders all work towards the same goal, but do now cooperate towards that goal. Cooperation between multiple stakeholders would result in more power, meaning they could makemore of an impact together. Most of the stakeholder‘s expectations could be met in this case, resulting in a satisfying design for most people. As a result of literature review and the performed interviews, a list of requirements is developed as a basis for the rest of the design of the bicycle network. The conclusion was made that not only a sufficient network needed to be designed, but that incentives for use were also needed. Therefore, the list of requirements is divided into three categories: infrastructure network, incentives for use and long-term guidelines and recommendations. The rest of the standardised design is based on the list of requirements. According to the requirement list, the new cycling network has been designed by greedy algorithm. The new plan can achieve 99.51%inhabitants with 320 metres of the walking distance. And it requires a new bridge for only cyclists and pedestrians’ use to cross Pinheiros River. Due to the demand of a bridge, a structural design is required. A literature review was performed, investigating the existing situation regarding the infrastructure. In the literature study, the different bridge types with their pro’s and con’s are described. Based on the existing situation and the literature study, a sound bicycle and pedestrian bridge design is designed. In this situation, for the standardised bridge, an arch bridge is the best choice. The standardised design allows for an efficient and fast design and execution process. This design process is obtained by using a parametric design in Rhinoceros and Grasshopper, so the design of the bridge can be used for multiple spans.
...
Nowadays the city of São Paulo has to deal with a lot of traffic jams. Extending the road network is no option and the public transport network cannot keep up with the capacity either. A solution must be found in another type of transport: cycling. The current bicycle infrastructure is not sufficient in terms of connectivity. In this research, a standardised bicycle network is developed for a part of the city, which can be used during future bicycle expansion projects in São Paulo. The development of the bicycle infrastructure concerns the whole city of São Paulo, resulting in a lot of interests being affected. The people behind these interests, the stakeholders, can have an influence over the project decisions, but do usually have conflicting interests. Therefore, these stakeholders are identified and analysed, through literature review and semi-structured interviews. In this case however, most stakeholders did not seem to experience any conflicts. The biggest problem in the development of the bicycle network, is that the stakeholders all work towards the same goal, but do now cooperate towards that goal. Cooperation between multiple stakeholders would result in more power, meaning they could makemore of an impact together. Most of the stakeholder‘s expectations could be met in this case, resulting in a satisfying design for most people. As a result of literature review and the performed interviews, a list of requirements is developed as a basis for the rest of the design of the bicycle network. The conclusion was made that not only a sufficient network needed to be designed, but that incentives for use were also needed. Therefore, the list of requirements is divided into three categories: infrastructure network, incentives for use and long-term guidelines and recommendations. The rest of the standardised design is based on the list of requirements. According to the requirement list, the new cycling network has been designed by greedy algorithm. The new plan can achieve 99.51%inhabitants with 320 metres of the walking distance. And it requires a new bridge for only cyclists and pedestrians’ use to cross Pinheiros River. Due to the demand of a bridge, a structural design is required. A literature review was performed, investigating the existing situation regarding the infrastructure. In the literature study, the different bridge types with their pro’s and con’s are described. Based on the existing situation and the literature study, a sound bicycle and pedestrian bridge design is designed. In this situation, for the standardised bridge, an arch bridge is the best choice. The standardised design allows for an efficient and fast design and execution process. This design process is obtained by using a parametric design in Rhinoceros and Grasshopper, so the design of the bridge can be used for multiple spans.