Evaluation of actions on concrete sleepers as design loads – influence of fastenings

Comment on: Toughness of Railroad Concrete Crossties with Holes and Web Openings. Infrastructures 2017, 2, 3

“…found in the German, French, and American literature (cited in detail in e.g., [6,7,16]). The values of actions calculated through these formulas, assuming the most adverse conditions, justify the sporadic appearance of cracks (on the order of 1%-2%), but in no case their systematic appearance in over 60% of the sleepers (approaching even 80% in some parts) laid in tracks under operation, as it was observed in the Greek railway network (at the 1980s).…”

“…The French State Railways'/SNCF's specifications, for the strength of sleepers, did not take into account the static tests at all! (see [6,19,20,26]). A thorough description of the Giannakos (2004) method for the loading and the strength of concrete sleepers is also described in [20,27], textbooks for Railway Engineering of the Civil Engineering Department of the University of Thessaly (2007-2014).…”

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The present brief comment is regarding the technical note "Toughness of railroad concrete crossties with holes and web opening", by Erosha K. Gamage, Sakdirat Kaewunruen, Alex M. Remennikov, and Tetsuya Ishida [1].I judge from my experience (please see some of my relevant publications [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] about loading and dimensioning of concrete sleepers; uploaded in http://giannakoskonstantinos.com/wp) that their technical note is of little value since it does not include dynamic testing of the sleepers/crossties, but it is based only on static tests. I briefly describe the research performed with me as the coordinator, for a period of over twenty years.

The investigation of railway matters in Greece had been undertaken during the development of the Greek Railways' network and the design, construction, and maintenance of new and upgraded (high-speed) lines planned for operational speeds of up to 250 km/h (155 m/h) and axle-load max = 22.5 t; this development has been co-financed by European Union/EU and the Greek Government, since the 1980s, and it is performed according to the EU's regulations and technical specifications.

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“…I judge from my experience (please see some of my relevant publications [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] about loading and dimensioning of concrete sleepers; uploaded in http://giannakoskonstantinos.com/wp) that their technical note is of little value since it does not include dynamic testing of the sleepers/crossties, but it is based only on static tests. I briefly describe the research performed with me as the coordinator, for a period of over twenty years.…”

“…One factor with a decisive influence on the value of the dynamic component of the actions is the value of the Non-Suspended (Unsprung) Masses/NSM of the vehicles and their behavior due to the dip of the (vertical) displacement of the track, the static stiffness coefficient of the track, the condition of the rail running table, etc. Two more parameters, that highly influence the value of the dynamic component of the actions, are the static and the dynamic stiffness coefficients of the pads of the fastenings; the static The results from Figure 1 led to a more exhaustive investigation of the extensive appearance of cracks on sleepers, which would lead to the development of a new methodology (Giannakos 2004 method) for the calculation of the actions on sleepers, which would be able to simulate and explain the phenomena that were observed in the Greek network (see [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]). One factor with a decisive influence on the value of the dynamic component of the actions is the value of the Non-Suspended (Unsprung) Masses/NSM of the vehicles and their behavior due to the dip of the (vertical) displacement of the track, the static stiffness coefficient of the track, the condition of the rail running table, etc.…”