Briefing: Limit states design of railway concrete sleepers

Recently updated information has raised a concern over not only the existing cost-ineffective design method but also the unrealistic analysis mode of railroad prestressed concrete sleepers. Because of the deficient knowledge in the past, railway civil engineers have been mostly aware of the over-conservative design methods for structural components in any railway track, which rely on allowable stresses and material strength reductions. Based on a number of proven experiments and field data, it is believed that the concrete sleepers which complied with the allowable stress concept possess unduly untapped fracture toughness. A collaborative research project run by the Australian Cooperative Research Centre for Railway Engineering and Technologies (RailCRC) was initiated to ascertain the reserved capacity of Australian railway prestressed concrete sleepers designed using the existing design code. The findings have led to the development of a new limit states design concept. This briefing highlights the conventional and the new limit states design philosophies and their implication to both the railway and the public community.

Introducing a new limit states design concept to railway concrete sleepers: An Australian experience

Over 50 years, a large number of research and development projects with respect to the use of cementitious and concrete materials for manufacturing railway sleepers have been significantly progressed in Australia, Europe, and Japan (Wang, 1996; Murray and Cai, 1998; Wakui and Okuda, 1999; Esveld, 2001; Freudenstein and Haban, 2006; Remennikov and Kaewunruen, 2008). Traditional sleeper materials are timber, steel, and concrete. Cost-efficiency, superior durability, and improved track stability are the main factors toward significant adoption of concrete materials for railway sleepers. The sleepers in a track system, as shown in Figure 1, are subjected to harsh and aggressive external forces and natural environments across a distance. Many systemic problems and technical issues associated with concrete sleepers have been tackled over decades. These include pre-mature failures of sleepers, concrete cancer or ettringite, abrasion of railseats and soffits, impact damages by rail machinery, bond-slip damage, longitudinal and lateral instability of track system, dimensional instability of sleepers, nuisance noise and vibration, and so on (Pfeil, 1997; Gustavson, 2002; Kaewunruen and Remennikov, 2008a,b, 2013). These issues are, however, becoming an emerging risk for many countries (in North and South Americas, Asia, and the Middle East) that have recently installed large volumes of concrete sleepers in their railway networks (Federal Railroad Administration, 2013). As a result, it is vital to researchers and practitioners to critically review and learn from previous experience and lessons around the world.

Urban Living Room: Inclusive U District Station Plaza Design

Thesis (Master's)--University of Washington, 2015

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station of the Grantham Railway

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station of the Grantham Railway by John Brown for February, 1856. This is signed by S.D. Woodruff, engineer, March 1856.

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station of the Grantham Railway

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station of the Grantham Railway by John Brown for March, April and May 1856.

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station of the Grantham Railway

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station of the Grantham Railway by John Brown for May, 1856. This is signed by S.D. Woodruff, engineer, June 3, 1856.

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station

Chart of estimate of work done on Port Dalhousie and Thorold Railway in the section between Geneva Street and Thorold Station of the Great Western Railway by John Brown for November, 1856. This is signed by S.D. Woodruff. The document is stained and damaged. Text is slightly affected, Nov. 1856.

Prices of John Brown’s contracts for Port Dalhousie and Thorold Railway from Geneva Street to Thorold Station

Prices of John Brown’s contracts for Port Dalhousie and Thorold Railway from Geneva Street to Thorold Station (1 page, handwritten), n.d.

The Dynamics of High-Speed Railway Bridges: A Review of Design Issues and New Research for Lateral Dynamics

The dynamic effects of high-speed trains on viaducts are important issues for the design of the structures, as well as for the consideration of safe running conditions for the trains. In this work we start by reviewing the relevance of some basic design aspects. The significance of impact factor envelopes for moving loads is considered first. Resonance which may be achieved for high-speed trains requires dynamic analysis, for which some key aspects are discussed. The relevance of performing a longitudinal distribution of axle loads, the number of modes taken in analysis, and the consideration of vehicle-structure interaction are discussed with representative examples. The lateral dynamic effects of running trains on bridges is of importance for laterally compliant viaducts, such as some very tall structures erected in new high-speed lines. The relevance of this study is mainly for the safety of the traffic, considering both internal actions such as the hunting motion as well as external actions such as wind or earthquakes [1]. These studies require three-dimensional dynamic coupled vehicle-bridge models, and consideration of wheel to rail contact, a phenomenon which is complex and costly to model in detail. We describe here a fully nonlinear coupled model, described in absolute coordinates and incorporated into a commercial finite element framework [2]. The wheel-rail contact has been considered using a FastSim algorithm which provides a compromise between accuracy and computational cost, and captures the main nonlinear response of the contact interface. Two applications are presented, firstly to a vehicle subject to a strong wind gust traversing a bridge, showing the relevance of the nonlinear wheel-rail contact model as well as the dynamic interaction between bridge and vehicle. The second application is to a real HS viaduct with a long continuous deck and tall piers and high lateral compliance [3]. The results show the safety of the traffic as well as the importance of considering features such as track alignment irregularities.

Dynamics of high-speed railway bridges: review of design issues and new research for lateral dynamics

Revisión y puesta al día de la publicaciones relacionadas con el diseño de puentes de ferrocarril de alta velocidad y nuevas investigaciones sobre dinámica lateral.