Understanding the vertical load path under static and dynamic loads in concrete crosstie and fastening systems

Concrete crossties;Fastening system;Dynamic loads;Wheel-rail interaction;Rail seat loads;Vertical load path

Manda, Kartik ; Lange ; David A.

关键词: Concrete crossties;    Fastening system;    Dynamic loads;    Wheel-rail interaction;    Rail seat loads;    Vertical load path;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/49525/Kartik_Manda.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

An understanding of the load path is necessary for developing a mechanistic design approach for the crossties and fastening systems. It is important to follow the flow of forces through the system to understand the demands on each individual component. In spite of extensive research focusing on the vertical load path a lack of clear understanding of the loads on the components exists. A number of failure mechanisms of ties, pads, insulators and fasteners still exist. This study focusses on understanding how the stiffness of the components in the system affects the flow of forces in the vertical direction. It has been identified that the stiffness of the support (ballast) underneath the crossties is crucial in determining the flow of forces. An extensive field testing program was undertaken at Transportation Technology Center (TTC) in Pueblo, CO by researchers from the University of Illinois at Urbana-Champaign (UIUC) in May 2013. Meticulous measurement of various parameters like loads, strains, rail seat pressure and displacements for the rail, pads, shoulders, ties were collected. Two sections of a track comprising of fifteen crossties each were chosen as test sections, one tangent section and one curved section. A TLV (Track Loading Vehicle) was used to apply static loads on the system. Freight and passenger trains were also deployed to study the response of the system under dynamic loading. A comparison between the static demands and the dynamic demands, as a result of the trains passing over the test section at different speeds, has been made which yields an important design factor. These understandings provide better insight into the loading demands on the system. An attempt has also been made to understand the response of the system under impact loads, a result of irregularities in the rail and wheel interface.