The Experts below are selected from a list of 283389 Experts worldwide ranked by ideXlab platform
Belete Dinku - One of the best experts on this subject based on the ideXlab platform.
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Soil-pile Interaction Soil-pile Interaction of pile in deep layered soil under seismic Excitation
Addis Ababa Science & Technology University, 2017Co-Authors: Belete DinkuAbstract:When lateral loads are applied on a pile, lateral deflection of the pile depends on the soil resistance and the soil resistance in turn depends on the pile deflection and this dependence is known as soil-pile Interaction. Dynamic soil-pile Interaction analysis has become an important field in civil engineering over the past years. Several major earthquakes that caused damage to buildings and other infrastructure have brought a lot of attention to response of pile foundations subjected to Dynamic loading. When a pile is subjected to a seismic excitation, deformation of the pile is caused by the movement of surrounding soil with the passage of seismic waves (kinematic Interaction) as well as the inertial forces applied by the superstructure due to its oscillation during the excitation (inertial Interaction). But, in actual engineering practice, pile responses are calculated using the pseudo-static approach which considers only the inertial Interaction effects, which essentially neglects kinematic Interaction effects. The field observations of pile failures after seismic events have highlighted the importance of incorporating kinematic effects in the design process. Hence some codes such as Euro code states those kinematic effects should be considered during the pile design process. However, still there is no definite method to techniques to analyses pile foundations for seismic loads considering both kinematic and inertial effects. In this research Finite Element Method (FEM) is used as the analyzing tool over the most widely used “Beam-On-Foundation” method, due to the reliability of FEM in simulating and analyzing of soil-pile Interaction problems. First the techniques were determined and incorporated in a three dimensional model developed using the general purpose finite element software ABAQUS to simulate the soil-pile system during a seismic excitation. The model was then extended to model the deep piles in multilayered soil profiles. For the investigation an actual soil profile was obtained from a site investigation. This consists of a deep marine sediment layer at the top of the profile and underlying soil layers with increasing stiffness and the scaled El-Centro were given to the soil-pile system. Also analyses were carried out varying the uppermost soft soil layer thickness to investigate the effect of soft soil layer thickness on pile behavior. Finally a parametric study was carried using soil profiles; with a deep soft soil layer. The analysis carried out show that the developed model has the capability of capturing important pile behavior under seismic excitations such as response due to kinematic and inertial Interaction effects, effect of soil stiffness on pile behavior, deflection patterns and permanent deformations. It highlights that, input to the superstructure in seismic analysis should be modified depending on the soil-pile Interaction effects, rather than using the original motion at the base of the structure which is the normal engineering practice. Moreover, analysis results show that pile behavior is unique and depends on many factors such as the nature of the soil profile it is embedded, soft layer thickness and properties of input motions. Furthermore, the developed model provides reliable techniques to simulate soil-pile Interaction which can be used in actual engineering practice and also can be extended for further research purposes. The analysis carried out show that the developed model has the capability of capturing important pile behavior under seismic excitations such as response due to kinematic and inertial Interaction effects, effect of soil stiffness on pile behavior, deflection patterns and permanent deformations. It highlights that, input to the superstructure in seismic analysis should be modified depending on the soil-pile Interaction effects, rather than using the original motion at the base of the structure which is the normal engineering practice. Moreover, analysis results show that pile behavior is unique and depends on many factors such as the nature of the soil profile it is embedded, soft layer thickness and properties of input motions. Furthermore, the developed model provides reliable techniques to simulate soil-pile Interaction which can be used in actual engineering practice and also can be extended for further research purposes
Wojciech Cellary - One of the best experts on this subject based on the ideXlab platform.
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building database applications of virtual reality with x vrml
international conference on 3D web technology, 2002Co-Authors: Krzysztof Walczak, Wojciech CellaryAbstract:A new method of building active database-driven virtual reality applications is presented. The term "active" is used to describe applications that allow server-side user Interaction, Dynamic composition of virtual scenes, access to on-line data, continuous visualization, and implementation of persistency.The use the X-VRML language for building active applications of virtual reality is proposed. X-VRML is a high-level XML-based language that overcomes the main limitations of the current virtual reality systems by providing convenient access to databases, object-orientation, parameterization, and imperative programming techniques. Applications of X-VRML include on-line data visualization, geographical information systems, scientific visualization, virtual games, and e-commerce applications such as virtual shops. In this paper, methods of accessing databases from X-VRML are described, architectures of X-VRML systems for different application domains are discussed, and examples of database applications of virtual reality implemented in X-VRML are presented.
Wenfeng Wu - One of the best experts on this subject based on the ideXlab platform.
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Research on Nonlinear Fluid-Solid Interaction Dynamic Lubrication in Floating Ring Bearings
Volume 6: Structures and Dynamics Parts A and B, 2009Co-Authors: Jinfu Yang, Zhongguang Fu, Shengbo Yang, Ce Chen, Ping Yuan, Wenfeng WuAbstract:An experiment of floating ring bearings and flexible rotor in a micro turbo-engine is carried out. Nonlinear behavior of fluid-solid Interaction in floating bearings is studied. And frequency characteristics And frequency characteristics of five typical vibrations regions in floating ring bearings test are presented. Furthermore, the difference and correlation between synchronous frequency characteristic in critical speed and subsynchronous whirl frequency harmonic response characteristic are illustrated._Based on the analytical expressions of load capacity and whirl frequency in single oil film lubrication bearings, the stability of inner and outer film in floating ring bearings is analyzed. It is shown that when half-speed oil whirl occurs in outer and inner oil film, the journal whirl ratios approach 0.5 and 0.3 respectively, which fairly corresponds with theoretical analysis. The paper can be a experimental and theoretical support for future performance evaluation and design of floating ring bearings.Copyright © 2009 by ASME
Pengfei Zhou - One of the best experts on this subject based on the ideXlab platform.
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investigation of concrete base roadbed surface contact variation induced vibration characteristics of vehicle slab track subgrade system considering fluid solid Interaction
Shock and Vibration, 2019Co-Authors: Qian Su, Pengfei ZhouAbstract:The excessive pumping of fines in saturated roadbed surface layer, which is induced by the fluid-solid Interaction under Dynamic loads from high-speed train, is a special form of high-speed railway subgrade defect reported recently. This can deteriorate the interface between nonballasted track structure bottom layer and roadbed surface layer and therefore lead to associated contact variation with the moving of trains. According to the Dynamic Biot’s equations known as u-p formulation and the vehicle-track coupling Dynamics theory, a vertical vehicle-slab track-subgrade coupling vibration model is developed to investigate the aforementioned contact variation-induced Dynamic behavior of the whole system considering the fluid-solid Interaction. Dynamic measurements from a field case study are adopted to verify the computation model proposed. Based on the numerical model validated, the effects of three contact variation statuses (continuous contact, vibrating contact, and contact loss) on Dynamic responses of track subsystem and subgrade subsystem, such as Dynamic pore-water pressure, vertical accelerations, and Dynamic displacements both in time and frequency domains, are investigated. Also, a sensitivity analysis involving rail speeds and lengths of contact loss zone is performed, and the critical length of contact loss zone is suggested.
Krzysztof Walczak - One of the best experts on this subject based on the ideXlab platform.
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building database applications of virtual reality with x vrml
international conference on 3D web technology, 2002Co-Authors: Krzysztof Walczak, Wojciech CellaryAbstract:A new method of building active database-driven virtual reality applications is presented. The term "active" is used to describe applications that allow server-side user Interaction, Dynamic composition of virtual scenes, access to on-line data, continuous visualization, and implementation of persistency.The use the X-VRML language for building active applications of virtual reality is proposed. X-VRML is a high-level XML-based language that overcomes the main limitations of the current virtual reality systems by providing convenient access to databases, object-orientation, parameterization, and imperative programming techniques. Applications of X-VRML include on-line data visualization, geographical information systems, scientific visualization, virtual games, and e-commerce applications such as virtual shops. In this paper, methods of accessing databases from X-VRML are described, architectures of X-VRML systems for different application domains are discussed, and examples of database applications of virtual reality implemented in X-VRML are presented.