RAIL CRC 1 A/Prof Alex Remennikov University of Wollongong, NSW Australia International Concrete Crosstie & Fastening System Symposium Research on Railway Sleepers Down Under RailTEC, University of Illinois at Urbana-Champaign

RAIL CRC Introduction Country Rail Network – ARTC / JHR

RAIL CRC Cooperative Research Centre CRC for Rail Innovation Phase II: Core Industry Partners: Ralcorp, QR, ARA, ARTC, and Rio Tinto Iron Ore. Universities: UoW, Monash, CQU, UQ, QUT, and UniSA >$100M Funding & 5 R&D Themes

RAIL CRC Cooperative Research Centre Economics, social, & environment Operations & safety Education & Training Engineering & safety Commercialisation & utilisation 4

RAIL CRC Ballast - Fouling Effect of Ballast Fouling subgrade pumping coal high ballast abrasion field investigation at Bellambi 5

RAIL CRC Ballast – Impact load Effect of Impact loads on ballast degradation ballast breakage impact load track stability ballast breakage 6

RAIL CRC Ballast – Impact load Effect of Impact loads on ballast degradation ballast breakage impact load track stability ballast breakage 7

RAIL CRC Ballast - NDT NDT for Ballast Quality ballast breakage track resilience fine particle contamination ballast layer subballast formation rail sleeper

RAIL CRC Ballast - NDT

RAIL CRC Rail Squats Rail Squat Strategies field investigation UQ/Monash/CQU finite element analysis metallurgical studies damage of components

RAIL CRC Short Pitch Irregularities CQU dipped welds Detection of Short Pitch Irregularities vibration based detection using AK Car axle box data integration algorithm

RAIL CRC Turnouts & Crossing Reduction of Impact due to crossing and turnouts Field Trials Sleeper/bearer pads Composite bearers

RAIL CRC 13 Concrete Sleepers Projects Innovative/Automated Track Maintenance and Upgrading Technologies Dynamic analysis of track and the assessment of its capacity with particular reference to concrete sleepers Key Industry Partners I ntroduction RAIL CRC 13

RAIL CRC 14  Concrete sleepers are designed according to a 19 th century deterministic method called ‘permissible stress design’ (e.g. AS , AREMA Manual for Railway Engineering (2010). I S THE CURRENT DESIGN OF CONCRETE SLEEPERS WRONG? RAIL CRC I ntroduction 14

RAIL CRC 15  Today almost all structural codes around the world use limit states design (aka Load and Resistance Factor Design LRFD), except for codes used in the design of concrete railway sleepers. I S THE CURRENT DESIGN OF CONCRETE SLEEPERS WRONG? RAIL CRC I ntroduction 15

RAIL CRC 16  There is a widespread perception in the railway industry that concrete sleepers have unused reserves of strength.  E.g., sleepers are generally replaced only because of non-design factors such as serious damage due to train derailment or inappropriate materials in the concrete mix or manufacturing faults. I S THE CURRENT DESIGN OF CONCRETE SLEEPERS WRONG? RAIL CRC I ntroduction 16

RAIL CRC 17  If concrete sleepers have unused reserve strength, increases in axle loads & train speeds may not, for example, need sleepers to be replaced with heavier ones.  The saving in expenditure around AU$100,000 per km of track could be achieved if the 22t sleepers in that section of track are found to not need replacing with higher rated sleepers. I S THE CURRENT DESIGN OF CONCRETE SLEEPERS WRONG? RAIL CRC I ntroduction 17

RAIL CRC 18  The current design approach is not wrong, but there is clearly a need for a method of designing and rating of concrete sleepers that is more rational than permissible stress design and which allows for the inherent variability of strength and of applied loads.  Development of the framework for designing concrete sleepers using limit states approach is discussed in this presentation. I S THE CURRENT DESIGN OF CONCRETE SLEEPERS WRONG? RAIL CRC I ntroduction 18

RAIL CRC 19 Limit States Design Framework for Prestressed Concrete Sleepers 19

RAIL CRC 20 RAIL CRC L imit states design Limit state deems that the strength of a structure is satisfactory if its calculated nominal capacity, reduced by a capacity factor , exceeds the sum of the nominal load effects multiplied by load factors . L IMIT STATES CONCEPT  × Nominal load effects ≤  × Nominal capacity where the nominal load effects (e.g. bending moments) are determined from the nominal applied loads by an appropriate method of structural analysis (static or dynamic). 20

RAIL CRC 21 RAIL CRC L imit states design A single once-off event such a severe wheel flat that generates an impulsive load capable of failing a single concrete sleeper. Failure under such a severe event would fit within failure definitions causing severe cracking at the rail seat or at the midspan. P ROPOSED LIMIT STATES OF PC SLEEPERS A time-dependent limit state where a single concrete sleeper accumulates damage progressively over a period of years to a point where it is considered to have reached failure. Such failure could come about from excessive accumulated abrasion or from cracking having grown progressively more severe under repeated loading impact forces over its lifetime. This limit state defines a condition where sleeper failure is beginning to impose some restrictions on the operational capacity of the track. The failure of a single sleeper is rarely a cause of a speed restriction or a line closure. However, when there is a failure of a cluster of sleepers, an operational restriction is usually applied until the problem is rectified. ULTIMATE FATIGUE SERVICE- ABILITY 21

RAIL CRC 22 RAIL CRC DEFINITION OF A “FAILED” SLEEPER abrasion at the bottom of the sleeper causing a loss of top; Australian railway organisations would condemn a sleeper when its ability to hold top of line or gauge is lost. abrasion at the rail seat causing a loss of top; severe cracks at the rail seat causing the ‘anchor’ of the fastening system to move and spread the gauge; severe cracks at the midspan of the sleeper causing the sleeper to ‘flex’ and spread the gauge; Only severe cracking leading to sleeper’s inability to hold top of line and gauge are considered as the failure conditions defining a limit state. L imit states design 22

RAIL CRC Limit States Design and In-track Loads 23

RAIL CRC Data Collection In limit states design the actual spectrum of forces is needed and in-field measurements are required. 12 months of WILD wheel impact data has been gathered from QR sites at Braeside & Raglan in Central Queensland. Approximately 5 million measurements of impacts means data is statistically robust. RAIL CRC 24

RAIL CRC Data Analysis 25 Variability of wagon weight for the nominal 28t (2 x 137 kN) axle loads. Mean force is 128 kN, standard deviation 13 kN.

RAIL CRC Data Analysis Straight line means forecast of impacts is reliable beyond the 12 months of data 26

RAIL CRC Other Factors Affecting In-Track Loads 27

RAIL CRC 28 Experimental Investigation of Dynamic Ultimate Capacities of Prestressed Concrete Sleepers for Limit States Design 28

RAIL CRC 29 T esting RAIL CRC D YNAMIC TESTING PROCEDURE Drop hammer impact testing machine Frame height = 6m Falling mass = 600 kg Impact load up to 2000 kN Impact velocity up to 10 m/s Operation efficiency 98% Working area = 5x2.5m 29

RAIL CRC 30 RAIL CRC T esting D YNAMIC TEST SETUP Railseat section Overall view 30

RAIL CRC 31 RAIL CRC T esting D YNAMIC TEST SETUP (VIDEO) 31

RAIL CRC 32 RAIL CRC T esting D YNAMIC TEST SETUP (VIDEO) 32

RAIL CRC 33 RAIL CRC T esting Impact forces between 500kN and 1600kN I MPACT RESISTANCE OF SLEEPERS 33

RAIL CRC 34 RAIL CRC T esting Impact failure of low profile sleeper at 1400kN I MPACT RESISTANCE OF SLEEPERS 34

RAIL CRC 35 RAIL CRC T esting Crack development under repeated loads I MPACT RESISTANCE OF SLEEPERS 35

RAIL CRC Proposed Ultimate Limit State Design Equations: where M Q is the moment induced in the sleeper by the design value of the wagon weight force; M I is the moment induced in the sleeper by the ultimate impact force I for the specified return period; 36 (based on Murray and Bian (2011))

RAIL CRC Experimental Determination of Impact Load – Railseat Moment Relationship 37

RAIL CRC Numerical Determination of Impact Load – Railseat Moment Relationship 38

RAIL CRC Case Study: Evaluate the Capacity of the Existing Concrete Sleepers to Carry Double Traffic Volume over next 10 years 39 Analysis based on working stress method Analysis based on ultimate limit state method

RAIL CRC 40 C onclusions RAIL CRC C ONCLUSIONS The proposed methodology has been successfully applied to the problems involving increased traffic volume and increased axle loads where the untapped reserve capacity allowed to not replacing the existing concrete sleepers with higher rated sleepers. Extensive investigations at UoW within the framework of the Rail-CRC have addressed the spectrum and magnitudes of dynamic forces, the reserve capacity of typical PC sleepers, and the development of a new limit states design concept. 40

RAIL CRC 41 Q &A Thank you for your attention Questions & Answers