Vision for Mechanistic Concrete Crosstie and Fastener System Design International Concrete Crosstie and Fastening System Symposium 8 June 2012  Urbana, IL J. Riley Edwards, Brandon J. Van Dyk, and Marcus S. Dersch

Outline Mechanistic Design Definition Other Applications Process Objectives Path Forward Data Collection and Analysis Implementation Questions and Comments

Current Design Process Mostly iterative, with focus on reduction of LCC reduction of the crosstie and fastening system Loading “conditions” empirically derived Some loading conditions extrapolated (AREMA C-30, Table 30-4-4) Process can be driven by production and installation considerations Option for Improvement  Mechanistic Design

Highway Example of Mechanistic Design MEPDG – Mechanistic-Empirical Pavement Design Guide Inputs – geometry, traffic, climate, materials Output – pavement responses to load, compute distresses and loss of ridability Apply to the rail industry?

What Is Mechanistic Design? Analytical approach  not an iterative design process Uses loading data to develop a design that functions under expected loading conditions Requires design for specific failures modes or performance indicators e.g. RSD, center cracking, post insulator wear, etc. Inputs – Crosstie and fastening system component geometry, traffic (axle load and tonnage), climate, materials Outputs – Tie and fastening system responses (stresses/strains) to loads, performance characteristics, wear rates?

Mechanistic Design Process Quantify System Input Loads (Wheel Impact Load Data (WILD), Instrumented Wheel Sets (IWS)) Qualitatively Establish Load Path (Free Body Diagrams, Basic Modeling, etc.) Establish the locations for load transfer, in need of further analysis and study Quantify Loading Conditions at each Interface / Component (Including displacements) Laboratory and Field Experimentation Analytical Modeling (Basic  FEM) Link Quantitative Data to Component Geometry and Materials Properties Go / No-Go Materials Decision

Mechanistic Design Process (Cont.) Relate Loading to Failure Modes (e.g. How does lateral loading relate to post insulator wear?) Understand Interdependencies taking advantage of modeling techniques Run parametric analyses Sensitivity of property vs. performance Development and Testing of Innovative Designs Novel rail pad, crosstie, insulator designs Geometry and materials improvements Establish Mechanistic Design Practices Adoption into AREMA Recommended Practices

Setting Design Thresholds Frequency Load (e.g. Rail Seat Load)

Z X Fcs Gcs Fts Fcs’ Gcs’ Fic Gic’ Fic’ Fos Gic Fos’ Fps’ Bpr Bpr’ Fps Gsc Fsc Fsc’ Gsc’ Subscripts b – rail base p – pad i – insulator clip bearing area c – clip s – shoulder o – insulator post t - tie Fbi Gbi’ Fbi’ Fbo’ Gbi Fbo Bbp Bbp’ Legend Reaction Friction Input Load F = Field G = Gauge B = Base Fst Gst

Distribution of Vertical Wheel Loads 95% 20 kips Source: Amtrak, Edgewood, MD, October 2011

Areas of Investigation Rail Stresses at rail seat Strains in the web Displacements of head/base Fasteners/ Insulator Strain of fasteners Stresses on insulator Internal strains Stresses at rail seat Midspan Global displacement of the crosstie Rail Seat Concrete Crossties

Planned Locations for Field Testing Monticello Railway Museum Transportation Technology Center (TTC) July 2012 November 2012 Spring 2013 Class I Railroads Amtrak BNSF Union Pacific Transportation Technology Center, Inc. High Tonnage Loop, Railroad Test Track Exciting summer of data acquisition Transportation Technology Center (TTC)

Future Work Evaluation and analysis of WILD data to better evaluate input loads Major discussion point from AREMA Committee 30, Subcommittee 4 (Concrete Tie Technology) Meeting Conduct laboratory and field testing to gain further insight on loads transferred through each component Development of greater understanding of dynamic interactions between system components Utilize output from instrumentation and modeling efforts to establish loading environment

Path Forward Development of System Level Tie and Fastener Model Field and Laboratory Testing of Components and Systems Materials Research and Improvements (all components) Understand how deterioration methods are related to differing axle loadings (important on shared corridors) Development of mechanistic design procedures  Adoption into AREMA Recommended Practices Ultimate objective  increase safety and lower life cycle costs of the crosstie and fastening system

FRA Tie and Fastener BAA Industry Partners: Acknowledgements FRA Tie and Fastener BAA Industry Partners: Funding for this research has been provided by the Federal Railroad Administration (FRA) Industry Partnership and support has been provided by Union Pacific (UP) Railroad BNSF Railway National Railway Passenger Corporation (Amtrak) Amsted RPS / Amsted Rail, Inc. GIC Ingeniería y Construcción Hanson Professional Services, Inc. CXT Concrete Ties, Inc., LB Foster Company

Contact Information Brandon Van Dyk Graduate Research Assistant e-mail: vandyk2@illinois.edu Marcus Dersch Research Engineer e-mail: vandyk2@illinois.edu Riley Edwards Lecturer e-mail: jedward2@illinois.edu