Abstract
The 2.5D finite/infinite element approach for simulating the ground vibrations by surface or underground moving trains is summarized. By assuming the soil profiles to be uniform along the railway, only a 2D profile of the soil perpendicular to the railway need be considered in the modeling. Besides the two in-plane degrees of freedom (DOFs) per node used for plane strain elements, an extra DOF is introduced to account for the out-of-plane wave transmission.
The soil profile is divided into a near field and a semi-infinite far field. The near field containing the train loads and structures is simulated by the finite elements, while the far field covering the soils with infinite boundary by the infinite elements, by which due account is taken of the soil radiation effect of the infinite boundary. Using the automated mesh expansion scheme devised by the speaker et al. (1996), the far field impedances for all the lower frequencies are generated consecutively from the mesh created for the highest frequency considered. The effect of rail irregularity is included in a load generation mechanism that takes into account the dynamic properties of the train as well. In the numerical examples, the isolation effect of elastic foundations under the concrete slab track is studied. Specifically, the advantage of the 2.5D approach in simulating the 3D wave propagation effect using the 2D element mesh is demonstrated. Compared with the conventional 3D approach, the present approach appears to be simple, efficient and accurate.
About the speaker
Prof Yeong-Bin Yang received his PhD in Structural Engineering from Cornell University in 1984. He joined th Department of Civil Engineering at National Taiwan University (NTU) in 1984, and was Dean of Engineering from 1995 to 2005. He was President of National Yunlin University of Science and Technology in from 2009 to 2013. He returned to NTU afterwards, and is currently Distinguished Professor of Civil Engineering at National Taiwan University.
Prof Yang’s researches focus on three areas: structural nonlinear analysis, bridge dynamic theories, and train-induced wave propagation, and he has published a book for each area. He is the editor-in-chief of International Journal of Structural Stability and Dynamics.
Prof Yang is a Member of the Austrian Academy of Sciences and the Chinese Academy of Engineering, and a Fellow of the American Society of Civil Engineers.
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