The National Academies

Rail Safety IDEA Project 46 [Active (IDEA)]

Adaptive Prestressing System for Concrete Crossties: Prototype Development

  Project Data
Funds: $100,000
Staff Responsibility: Inam Jawed
Research Agency: University of Illinois at Urbana-Champaign
Principal Investigator: Bassem Andrawes
Effective Date: 10/1/2021
Fiscal Year: 2021

This project will develop and test full-scale prototypes of an innovative Adaptive Prestressing System (APS) for railroad concrete crossties. The work will be carried out in two stages. Stage 1 work will focus on the design and fabrication of full-scale APS components that will be incorporated in the final prototype crosstie design: An effective APS connection will be developed, based on investigating two connection options, namely, mechanical couplers and welding. This will include testing available coupler designs in the market with large-size SMA wires, and use welding to incorporate short segments of SMA (fuses) within the APS. A duct system will be developed to enclose the APS. Various types of ducts, including plastic ducts, metal ducts, and ducts made of fiber reinforced polymeric (FRP) material will be subjected to repeated mechanical and thermal loadings in the laboratory environment. A new scheme for heating APS embedded in concrete will be developed. The scheme will potentially incorporate an electrical outlet, where external portable power supply can be plugged in to passing the electrical current in APS fuses. Work in Stage 2 will focus on assembling the APS components into a full-scale tie reinforced with APS. Prototype designs with various APS configurations will be considered, following AREMA Chapter 30 guidelines. The ties will then be tested in the laboratory and field to examine their performance under various loading conditions. Prior to prototype testing, the response of the APS ties when placed in track will be numerically analyzed using finite element method. Multiple tie designs will be explored. The designs will incorporate different APS configurations that provide prestressing at various locations and orientations across the tie. The analyzed tie designs will be fabricated and a plan will be set up to install strain gauges and thermocouples internally in the ties to collect strain and temperature data, respectively during testing from the APS fuse and steel wires. The fabricated ties will be tested at the university laboratory and in the field at the Transportation Technology Center, Inc. (TTCI) in Pueblo, Colorado. The laboratory tests will include flexural testing of ties under center binding and rail seat loading conditions as per AREMA recommendations. The data acquired will be analyzed to assess the reliability of the APS ties behavior under various loading conditions. The final report will include all relevant data, methods, designs, and conclusions along with guidance on how to use the system in the field.

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