Modeling the Lateral Load Distribution for Multiple Concrete Crossties and Fastening System

UIUC Project Information


NuRail Project IDNURail2014-UIUC-R09
Project TitleModeling the Lateral Load Distribution for Multiple Concrete Crossties and Fastening System
UniversityUniversity of Illinois at Urbana-Champaign
Project ManagerBarkan
Principal InvestigatorAndrawes
PI Contact InformationPhone: NA Email: andrawes@illinois.edu
Funding Source(s) and Amounts Provided (by each agency or organization)$65,000 NURail Funds
Total Project Cost$65,000
Agency ID or Contract NumberDTRT12-G-UTC18 (Grant 1)
Start Date2014-12-01
End Date2016-05-31
Location
Brief Description of Research ProjectThe primary objective of this project is to study the effect impact load (dynamic load) resulting from defects in the rail and/or wheel (e.g. Wheel flat) and better understand the mechanisms through which this load transfer within various track components. The study will help shed the light on some of the uncertainty associate with impact factor and what factors govern it. Further, these impact forces are thought by many as one of the reasons for long term deterioration of track systems. Therefore, understanding how to minimize these loads is essential. This project will aim at capitalizing on the advances in the Finite Element Analysis (FEA) efforts developed over the last few years by the PI and his group to model crossties and fastening systems. Finite element method will be utilized in this project to study the response of multiple crossties under impact wheel loads while considering different fastening system components in the model. The study will first focus on validating the FE model through using field data, and then using the validated model in a comprehensive parametric study. The parametric study will focus on understanding the factors affecting the dynamic impact factor and how track conditions and mechanical properties of the rail seat could possibly affect these factors. Recommendations will be developed to minimize the impact forces on track systems.
Describe Implementation of Research Outcomes (or why not implemented)Railroad grade crossings are potential conflict points between train and highway vehicles, and train and pedestrians. The crossings pose a risk to all the travelers and the degree of risk depends on many factors such as volume train, volume of vehicles, presence and operation of traffic control devices (TCD), speed of trains and vehicles, geometry of the crossing, interaction with interconnected intersection, pedestrians, no of tracks, etc. To assess the safety and risk of RR crossing, one may utilize aggregated data for the entire state or the country. Analysis of the aggregated data may be useful in establishing correlation among variables that are important at system level (state or country), but might not be very useful for a given crossing. On the other hand, a micro-level analysis determines the risk of crash at a given location (or a set of similar locations). The crash risk at a given crossing will depend on past crash history at that location, as well as the relation amount different geometric design elements of roadway and railway, signing and sign distances, type of development in the surrounding area, type of travelers, characteristics of those who got involved in crashes, and other factors. At the micro-level one considers the uniqueness of each crossing and develops a risk factor for such crossings. Then, the safety and risk at system level can be determined based on these individual safety and risk assessments. To conduct the micro-level safety ad risk assessment, the following tasks will be done.

1. Literature review: There is lack of information related to the work that has been done in the area of dynamic load effects on track systems. Although a quick inspection will reveal that the literature available on static load is far more than that on dynamic loads, there is no comprehensive idea on the extent done on the later. The first phase of the project will focus on conducting a thorough review of the literature in this area, especially identifying the studies that focused on the FE modeling of railroad track systems.
2. Model Development and Validation: The developed FE models should include with an acceptable degree of accuracy the effect of interactions between various track components including fastening system components (clips, pads, shoulders, etc.). Developing these models require in depth analysis of single-tie models first in order to obtain realistic values of the equivalent stiffness and mechanical properties of the springs elements which will comprise the boundary conditions for the multiple-tie model. The developed FE model will be validated using field data acquired under a wheel flat condition.
3. Conduct Parametric Study: The developed multiple-tie model will be utilized in conducting detailed parametric study that will aim at understanding the effect of various track components on the distribution of impact load between multiple crossties. In addition to varying the material and geometric properties of the tie and fastening system, the load magnitude, speed, and tie spacing will also be varied. In the light of the results of the parametric study, relationships between the location of the load along the track and the dynamic load impact factor will be established.

The primary deliverables of this project will be conference and peer-reviewed journal papers submitted to both structural and railroad conferences and journals, respectively.
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Impacts/Benefits of Implementation (actual, not anticipated)It is understood among researchers and practitioners in the railroad industry that interaction between components plays significant role in defining the safety and serviceability of railroad track systems. With the increasing interest in replacing timber crossties with concrete crossties, there is a dire need to understand better the interaction between multiple concrete crossties especially under dynamic loading. This relates specifically to the USDOT's strategic goal of "State of Good Repair" as well as "Safety" given the implications of deterioration of the rail under repeated large impact forces. Understanding impact load distribution mechanism and its controlling parameters will allow engineers to minimize the negative effects of dynamic loads with time. This will protect both crossties and fastening system from excessive deterioration, which had proven to have significant negative implications on the long-term safety and serviceability (state of repair) of railway infrastructure.
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Completedyes
Final ReportNURail2014-UIUC-R09_Final_Report_(Andrawes).pdf