A railway track is a structural composure of many elements. Railway track analyses requires analyses for the interaction between these elements and the interaction between the track and the vehicle passing over the track. Various design models have been developed to simplify the analysis of railway tracks and to establish appropriate design criteria. Winkler's representation of the subgrade support as a continuous structure with independent springs was adapted to railway tracks by Zimmermann that further evolved into what is known as the Beam on Elastic Foundation Theorem (BOEF) today. A soil and structure interaction model based on BOEF theorem, frequently used by engineers to analyze the response of continuously supported structures on bearing layers, provides estimates for the distribution of deflections, bearing pressure, shears and moments along a continuously supported structure, such as a plate, by subgrade. This study aims to provide an in-depth and an explicit solution to the 4th order differential equation of BOEF and serve as a resource for those who are interested in this topic. This study will also present the historical development of the BOEF model, its use in railway track analysis, as well as its underlying assumptions in terms of structural behavior.
Bir demiryolu hattının esneme direnci, hat tasarımında göz önünde bulundurulması gereken en önemli parametrelerden biridir. Bu değerin optimum değerinden düşük olması hattaki oturmaları artırırken, yüksek olması zaman içerisinde hat elemanlarında yıpranmalara neden olur. Bununla birlikte, hat esneme direncinin hat boyunca değişmesiyle dinamik darbe kuvvetleri artarak hattın bozulma sürecini hızlandırır. Hat esneme direnci; hattı oluşturan malzeme özelliklerine, zemin tabakasındaki yerel farklılıklara, hattaki bazı özel durumlara ve hat bileşenlerinin geometrisine bağlı olarak değişmektedir. Aynı zamanda araç-hat etkileşimi de hattın teker kuvvetine karşı gösterdiği tepkiyi etkilemektedir. Bu çalışma, demiryolu hat tasarımlarında esas alınacak olan hat esneme direncini tartışan temel bir kaynak olmayı hedeflemektedir. Bu anlamda yapı-zemin etkileşimini inceleyerek, taşıyıcı zeminin yanı sıra hat üstyapısına ait mekanik ve geometrik özelliklerin, hat ve zeminin bir bütün olarak düşey yükler altındaki tepkisini etkilediğini elastisite teorisine dayalı modeller üzerinden göstermektedir. Daha sonra, araç-hat etkileşimi ele alınmış ve hatta ait tüm parametreler aynı kalsa dahi sadece dingil mesafesindeki değişim nedeniyle hat tepkisinin değiştiği gösterilmiştir. Son olarak, hatta ait mekanik ve geometrik niteliklerin eşdeğer hat esneme direnci üzerindeki etkileri açıklanmıştır.
With the latest technological advances, intelligent personal assistants are becoming part of our daily lives. In the future, with improvements in artificial intelligence techniques, it is foreseen that individuals' life management will be greatly assisted by intelligent personal assistants. Today, it seems that intelligent personal assistants have not yet reached their full potential. For more efficient use, more technical developments are needed, especially in terms of natural language processing. In order to that, areas which need improvement must be determined based on which challenges are faced. In order to develop more efficient solutions for problems, an initial fundamental evaluation is necessary. In this work, features of intelligent personal assistants are examined and existing applications are referred to. For a better understanding of what features an intelligent personal assistant must contain, a literature review was completed. In-use features which should be improved in the future, challenges challenges which need to be overcome, areas which could be made more efficient, and how to increase usage are determined.
Dynamic impact forces occur on railway tracks due to the presence of roughness of the track and the wheel and relate to the train speed and the rate of change of roughness. Variations in track profile and track stiffness and variations in wheel circularity are the causes of roughness. Quantification of the dynamic impact forces is not an easy task due to the complexity of the mechanics of the rolling stock interaction with the railway track. A number of experimental studies have led to an understanding of the dynamic impact forces, yielding a set of conservative and case-specific empirical equations. There are also many calculation-intensive numerical techniques, relying on iterative calculations seeking to converge to a state of temporary equilibrium for the analyzed structural domain within small-time increments. These techniques provide detailed and valuable information for the stresses that develop within the many components of the railway track. However, such numerical techniques rely on expensive computational tools that require experienced users to apply and interpret their results. The sheer amount of representative structural and material data input required to define the analyzed structural domain of the railway track properly is also an important task to accomplish in order to conduct a meaningful analysis. The second author developed a simple analytical method that can provide an accurate analysis for the dynamic impact forces on any railway track relying on track stiffness as the only mechanical railway track parameter. This paper introduces an ongoing study led by the second author and provides an insight into how a designer or a track maintainer can apply the Bezgin Method to estimate dynamic impact forces that may occur in rail-ends and within turnouts. This paper will also discuss how one can judge the conditions for ballast pulverization or slab cracking should these conditions exist.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.