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...ctive formulations of the desiredsdynamic model. The traditional spring-dashpotsmodel has been applied to the various studies onsvertical vibrations of railway tracks (Grassie & Cox,s1984; Cai, 1992; =-=Knothe & Grassie, 1993-=-; Oscarsson,s2002). In recent years, the state-dependent model ofsrail pads, where an additional spring is presented insseries with the dashpot, has been proposed for usesas an alternative model for r...

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... simple quasi-staticsloads. These forces are often called as ‘dynamic wheel/rail’ or ‘impact’ forces. The typical impact loadingssdue to train and track vertical interaction has been presented in ref =-=[3]-=- with particular reference to thesshapes of the typical waveforms of impact loads generally found in railway track structures.sFigure 1 Typical ballasted track structuresIt is believed based on the in...

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...from staticsor quasi-static loads, ascribed to a dynamic impact factor multiplying with the wheel load. Interestingly, thesdesign life span of the concrete sleepers is also considered around 50 years =-=[2]-=-. In reality, the nature ofsloading conditions on railway track structures is somewhat time dependent. Major research attention hassbeen focussed on vertical static and dynamic forces as they are the ...

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...linear dynamic behaviour of rail pads, althoughsit is evident that deterioration rate has significantsinfluence on the dynamic rail pad properties thatsaffect the dynamic responses of railway trackss(=-=Grassie & Cox, 1984-=-; Wu & Thompson, 1999). Asreason is the lack of information on the dynamicsbehaviour of rail pads at different ages, and thesknowledge of the dynamic wheel-load distributionsto rail pads and other tra...

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...ng the objective formulations of the desiredsdynamic model. The traditional spring-dashpotsmodel has been applied to the various studies onsvertical vibrations of railway tracks (Grassie & Cox,s1984; =-=Cai, 1992-=-; Knothe & Grassie, 1993; Oscarsson,s2002). In recent years, the state-dependent model ofsrail pads, where an additional spring is presented insseries with the dashpot, has been proposed for usesas an...

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...n,s2002). In recent years, the state-dependent model ofsrail pads, where an additional spring is presented insseries with the dashpot, has been proposed for usesas an alternative model for rail pads (=-=Fenander, 1998-=-;sde Man, 2002; Neilsen & Oscarsson, 2004; Maes et al,s2006; Remennikov et al, 2006).sDe Man (2002) noted a benefit of the state-dependentsmodel that the model can separate influencessFigure 1: Rail p...

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...our of rail pads, althoughsit is evident that deterioration rate has significantsinfluence on the dynamic rail pad properties thatsaffect the dynamic responses of railway trackss(Grassie & Cox, 1984; =-=Wu & Thompson, 1999-=-). Asreason is the lack of information on the dynamicsbehaviour of rail pads at different ages, and thesknowledge of the dynamic wheel-load distributionsto rail pads and other track components. Curren...

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...amic characteristics of resilient pads have been found recentlysin literature (Grassie, 1989; Van’t Zand, 1993; desMan, 2002; Remennikov and Kaewunruen, 2005;sKaewunruen and Remennikov, 2005a, 2005b; =-=Remennikov et al., 2006-=-; Maes et al., 2006). Interestingly, some studies have been based on a twodegree-of-freedom (2DOF) model (Fenander, 1997,s1998; Thomson, et al., 1998; Knothe et al., 2003).sExcept Maes’s work that mea...

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...y the processes whereby concrete sleepers in particular carry those actions. In addition,scracks in concrete sleepers have been visually observed by many railway organizations. As noted in thesreview =-=[4]-=-, the principal cause of cracking is the infrequent but high-magnitude wheel loads produced by assmall percentage of “bad” wheels or railhead surface defects. Those loads are of short duration but of ...

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...RETE RAILWAYsSLEEPERSsModeling and its validationsIt has been established that the two-dimensional Timoshenkosbeam model is a suitable option for modeling concrete sleepers (Neilsen, 1991; Cai, 1992; =-=Grassie, 1995-=-). In this investigation, the finite element model of a concrete sleeper hassbeen previously developed and calibrated against the numerical and experimental modal parameters (Kaewunruen & Remennikov, ...

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...sing wires are of high quality and the strength will notschange during time. The tested average compressive strength of cored concrete is 88.5MPa. This valueshas been corrected according to AS1012.14 =-=[24]-=-. The details of static responses, rotational capacity, postfailure mechanisms, and residual load-carrying capacity of the prestressed concrete sleepers under staticsloading can be found in ref: [25-2...

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...e determined at thesresonant frequency, when using an impact hammersas the exciter. A number of investigations of the dynamicscharacteristics of resilient pads have been foundsrecently in literature (=-=Grassie, 1989-=-; Van’t Zand,s1993; de Man, 2002; Remennikov & Kaewunruen,s2005; Kaewunruen and Remennikov, 2005a; 2005b;sRemennikov et al, 2006; Maes et al, 2006). Interestingly,ssome studies have been based on a tw...

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...d railway track is often used for accessing to remote and rural area. The financialsviability of the ballasted track relies on its cost-effectiveness in construction, maintenance, and renewal.sEsveld =-=[1]-=- stresses that ballasted railway track has many advantages; for example, the construction costssare comparatively low, the maintenance and repair of track and its components are convenient, it has hig...

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... Remennikov & Kaewunruen,s2005; Kaewunruen and Remennikov, 2005a; 2005b;sRemennikov et al, 2006; Maes et al, 2006). Interestingly,ssome studies have been based on a two-degree-offreedom (2DOF) model (=-=Fenander, 1997-=-; 1998;sThomson et al, 1998; Knothe et al, 2003). From thesliterature, single-degree-of-freedom (SDOF) dynamicsmodel has popularly been applied to the laboratoryssetup of a number of investigations. I...

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...f resilient pads have been foundsrecently in literature (Grassie, 1989; Van’t Zand,s1993; de Man, 2002; Remennikov & Kaewunruen,s2005; Kaewunruen and Remennikov, 2005a; 2005b;sRemennikov et al, 2006; =-=Maes et al, 2006-=-). Interestingly,ssome studies have been based on a two-degree-offreedom (2DOF) model (Fenander, 1997; 1998;sThomson et al, 1998; Knothe et al, 2003). From thesliterature, single-degree-of-freedom (SD...

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...thesnegative bending moment tend to significantly increase oversa wide range of frequency and this may cause wear to cribsballast (Kaewunruen & Remennikov, 2009a) and may radiateslow-frequency noise (=-=Thompson, 2010-=-). In contrast, the losssof ballast support tends to suppress the dynamic positivesmoments at the mid-span. This is because the support condition generally redistributes the load and bends the sleeper...

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... factors, including relative masses, velocities, contact zone stiffness, frequency ofsloading, precision of impact, and locally energy-absorbed area [14-15]. Regarding to railway sleepers, Ye,set al. =-=[16]-=- and Wang [17] investigated the resistance of concrete railroad ties to impact loading. Theirsstudy focused on the effect of material uses on the ultimate capacity of prestressed concrete sleepers.sHo...

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...uding relative masses, velocities, contact zone stiffness, frequency ofsloading, precision of impact, and locally energy-absorbed area [14-15]. Regarding to railway sleepers, Ye,set al. [16] and Wang =-=[17]-=- investigated the resistance of concrete railroad ties to impact loading. Theirsstudy focused on the effect of material uses on the ultimate capacity of prestressed concrete sleepers.sHowever, it was ...

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...a simplified prediction for the ultimate capacity of concrete sleepers. The keyshindrance was about how rail pad really affect the system impact responses and how much of that effect.sWakui and Okuda =-=[18]-=- have later proposed a simplified technique to predict the ultimate capacity ofsconcrete sleepers but they failed to prove it. The strain rate and loading rate have been taken into accountson the basi...

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...hich is slightly higher than the static energy absorption.sThis phenomenon is ascribed to the effect of strain rate, as when the strain rate is high the concretesmaterial becomes stronger but brittle =-=[9,10,20]-=-.s5. CONCLUSIONSsThe nature of loading on tracks is of impact loading. Current design manner omits those actions since thesexisting knowledge is insufficient. The main aim of this study is to develop ...

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...ds is about 45-65 MN/m. It shouldsbe noted that the available data from industry aresassociated with the rail pad type testing setup andsspecific loading regime, as prescribed in AS1085.19s(Standards =-=Australia, 2001-=-).sTable 2 gives the general data of the pad specimens.sThese two specimens of rail pads are the availablestypes, which are commonly used in Australiansrailway networks for either passenger or heavysh...

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...search effort at the University of Wollongong is to evaluatesand compare the resistance capacities of concrete sleepers under static and impact loads.sFrom the literature review, Sukontasukkul et al. =-=[9,10]-=- found that concrete strength under impact loadingsshows different behavior from that under static loading. Considerably, the concrete material behaves in asmore brittle manner, and increases in stren...

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...search effort at the University of Wollongong is to evaluatesand compare the resistance capacities of concrete sleepers under static and impact loads.sFrom the literature review, Sukontasukkul et al. =-=[9,10]-=- found that concrete strength under impact loadingsshows different behavior from that under static loading. Considerably, the concrete material behaves in asmore brittle manner, and increases in stren...

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...cribed by a number of factorssthat include relative masses, velocities, contact zonesstiffness, frequency of loading, precision of impact,sand the area of local energy absorbed (Banthia et al.,s1987; =-=Kishi et al., 2002-=-a, 2002b; Hughes and AlDafiry, 1995). Recently, Ando et al. (2001) have developed a simple elasto-plastic finite element modelsof half-columns subjected to lateral impact loading.sThe numerical result...

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...strong isolated floor in theslaboratory. The thick rubber mat was used to replicate the ballast support. It is found that the test setupsrepresents the concrete sleepers in general soft track systems =-=[21]-=-. To apply impact loads, the dropshammer used has the weight of 5.81kN. At the railseat was installed the rail with fastening system tostransfer the load to the specimens. The roller was attached to t...

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...nnected to the National Instrument data acquisition system. The relationshipssbetween contact impact force and bending moment at railseat of the concrete sleepers are presented insthe companion paper =-=[22]-=-. After applying the impact loads, the energy absorptions and impact responsesscan be achieved. The comparative study of both static and impact energy absorption of prestressedsconcrete sleepers was c...

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...ative Research Centre for Railway Engineering andsTechnologies (Rail CRC). The total length of the sleeper is 2.15m with the gauge length of 1.69m. Thesdetails can be found in another companion paper =-=[23]-=-. The broad gauge sleepers obtained are commonlysused in the heavy haul coal lines of Australian railway network, especially in the state of Queenslandsrailway system. Figure 2a shows the cross sectio...

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...sectional analysis of prestressed concrete section, which was calculated from a computerspackage, Response-2000. This package relied upon the modified compression field theory for concretesstructures =-=[25]-=-. The input data include: the measured initial strain of wires due to prestressing is abouts6.70 mm/m, and each prestressing wire has a proof stress of 1860 MPa. The tested compressive strengthsof con...

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...tion responses at mid-span and at railseat of the railway concretessleepers.sThe displacement responses can subsequently obtained from the integration of accelerationsresponses. Based on Birch et al. =-=[27]-=-, the actual energy absorbed by the sleepers can be approximatelyscomputed from the multiplication between maximum impact load and the maximum displacement spectrasintegrated from the acceleration res...