Joep Tunnissen Abs

8/9/2019 Joep Tunnissen Abs

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Track-Bridge Interaction on High-Speed Railways 1

DYNAMIC ASPECTS OF THE HIGH-SPEED RAILWAY BRIDGEACROSS THE HOLLANDSCH DIEP

J.T.F.M. TÜNNISSENJoep Tünnissen Dynamic Engineering Consultancy

Veghel - The Netherlands

ABSTRACT

The structures and track system which are part of the Dutch High-Speed Railway connection between Amsterdam and Paris, have all been analyzed for their dynamic behavior with regardto structural integrity and passenger comfort. This paper describes the general approach of

these dynamic analyses as performed in the High-Speed Line-Zuid project, and goes into moredetail with regard to bridge-track interactions at the bridge across the Hollandsch Diep, one ofthe most eye-catching and largest structures in this project. Relevant issues are the optimizationof the level of passenger comfort by introduction of a pre-camber in the alignment of the tracksystem and the dynamic behavior of the steel transition slabs, which as a special structure inthe track system allow for the horizontal expansion and contraction of the bridge.

1. INTRODUCTION

October 2007, the Dutch part of the High-Speed Railway connection between Amsterdam andParis nears its completion and thereby its goal to reduce the travelling time between both citiesto just 3 hours. In the 125 kilometers from Amsterdam, via Rotterdam to the Belgium border,

of which 85 kilometers have been destined for high-speed railway, trains will pass 170different structures, designed to cope with train velocities up to 300 km/h.

In the 2nd half of the 90s the HSL-Zuid Project-organization, representing the Dutch State

Department of Transportation, developed the visualization and engineering tools for thearchitectural and structural elements in the High-Speed Line-Zuid project. Due to its magnitudeand complexity it was decided to divide the contract into 7 subcontracts. 6 of thesesubcontracts dealt with the design and construction of the railway structures, each covering aseparate part of the track. They were granted to different joint ventures between contractors in


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2 Track-Bridge Interaction on High-Speed Railways

the year 2000. The 7th subcontract covered the design and construction of the track system aswell as the future maintenance of the entire railway system and was granted to Infraspeed in2002. The author has been a member of the design team in 4 out of these 7 subcontracts, as anadvisor on dynamic aspects and as the responsible party for the dynamic analyses performed on

the primary (main structures and track system) and secondary (architectural elements and noise barriers) structures.

The Dutch terrain has required many adaptations to the high-speed railway structures and tracksystem as the track encounters highways, rivers, canals, ditches and environmentally importantareas on its way. Together with the necessity for piled foundations, due to the soft clay type ofsoil in the western part of the Netherlands, the track has become a chain of different structureswith dilatations generally every 20 to 30 m. Dealing with the design criteria concerning the

dynamic behavior of these structures and the implementation of a ballastless track system, has

made the HSL-Zuid project a challenging engineering experience.

2. HIGH-SPEED RAILWAY STRUCTURES IN HSL-ZUID

The natural and man-made obstacles in the path of the track, the need for pile foundations andthe ever developing engineering and architectural insight during the design phase, have led to avariety of structures. Some of these structures are highly visible, such as the elevated long-

viaducts near Hoofddorp and Bleiswijk (see figure 1), and the bridge crossing the HollandschDiep, which with a total span of 1192 meters is the longest HSR-bridge between Amsterdamand Paris (see figure 2). Others are hardly noticeable, such as the settlement-free slabs, whichcover about 33 km of the track and with their typical length of 30 m per slab often provide thelink with other types of structures. Except for the train passengers, some major achievements

are not visible at all, such as the Ringvaart aqueduct and the tunnels underneath the GreenHeart, with a diameter of almost 15 meters, one of the largest drilled tunnel in the world, andthe rivers Oude Maas and Dordtsche Kil.

Due to the soft clay type of soil in the western part of the Netherlands most of these structuresare supported by pile foundations, reaching into the Pleistocene sand bed. Only in the last 3.5kilometers towards the Belgium border the sand bed reaches the surface and provides a solidfoundation. At this location the transition into a ballast track is established in order to connectto the Belgium part of the high-speed railway track.

Figure 1: Long-viaduct (6 km) near Bleiswijk (Photo: JTüDEC)


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Figure 2: Bridge across the Hollandsch Diep (Photo: JTüDEC)

The prize-winning design for the bridge across the Hollandsch Diep by architects Benthem &Crouwel, is a result of a competition held by the HSL-Zuid Project-organization. Theoptimization of the design and the final construction of the bridge was in the hands of HSLDrechtse Steden, a joint venture of contractors responsible for the track between the city ofBarendrecht and the southern end of the bridge. Consisting of steel box-girders and U-shapedsections topped by a concrete deck, the 10 main spans measure 105 m each to coincide with the

spans of the old railway bridge located next to it. The V-shaped hammer-pieces with a lengthof 45 m and a maximum height of 11.40 m are interconnected by 60 m long field members. In

the engineering phase minor changes to the columns were introduced in order to obtain amaximum spread of the rubber bearings. The increase of restraint at these locations resulted inan increase of the natural frequency of the bridge which was beneficial to the level of passenger comfort.

3. RHEDA 2000 TRACK SYSTEM

The choice of a ballastless track system is based on economics, ease of maintenance andfavorable experiences with this system abroad. However, due to the soft soil conditions and thevariety of supporting structures with their inherent need for dilatations, the classical solution of

a continuous ballastless track could not be implemented in the HSL-Zuid project without somemajor adjustments. The task of coming up with a solution was given to Rheda 2000 vof, whichled to the introduction of 2 different types of track. One, a continuous slab poured directly ontothe structure in areas which are relatively insensitive to settlement such as tunnels and slabs on

embankment and two, a jointed slab which is poured on an intermediate layer, consisting of a 4mm thick poly-propylene geo-textile op top of the structures in settlement sensitive areas. The jointed slab is anchored to the structure in pre-designated free-drilling zones by means ofHILTI high quality stainless steel dowels with a diameter of 40 mm. This is the mostcommonly type used throughout the track (67%) for structures such as the settlement-free


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slabs, viaducts and bridges with dilatations approximately every 15 to 30 meters, but also onthe bridge across the Hollandsch Diep which is categorized as being sensitive tosettlement/vertical deflection.

In the 163 km of Rheda 2000® slab track system, the rails are the only continuous elements

connecting adjacent structures. They are held in place by a Vossloh type IOARV 300 rail-

fastening system which is provided with a highly elastic intermediate layer. These layers areresponsible for the transfer of horizontal and vertical forces into the Pfleiderer type B355W60M concrete bi-block sleepers. The Rheda 2000

® slab track system is completed by casting

the prefab concrete sleepers into a reinforced concrete slab on site. The reinforcement consistsof lattice trusses which provide stable dimensions and assures the required gauge of the track.The concrete slab grade B35, as used in the HSL-Zuid project, has a standard height, without

cant, of 240 mm and a width of 2600 or 2800 mm, depending on the location. The slab is

reinforced throughout its entire length for systematic prevention of cracks. See figure 3.

240

500

232

2600

3000

Fastening IOARV 300

Sleeper B355 (c.t.c. 650 mm typical)

Dowel

Intermediate layer free drilling zone

Settlement-Free Plate

Figure 3: Rheda 2000 slab track system on settlement-free plate

The interconnecting components of the Rheda 2000® track system, being the stainless steel

dowels and the intermediate layer have undergone several tests in order to determine theircapacity to withstand fatigue loadings (dowels) and to establish the stiffness characteristics andfrictional behavior under static and dynamic loadings (intermediate layer). Dynamic analyseshave been performed on the interaction between structures and track system near transitions,especially with regard to the dynamic forces in the rail-fastening system.

Due to the fact that the engineering phase for the structures started 2 years prior to that of thetrack system, assumptions were made with regard to the system’s mass ranging from 650 to

3750 kg/m per track. Without cant, the mass of the Rheda 2000® slab track with one pair of

UIC60 type rails eventually comes down to approximately 1800 kg/m per track.


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4.

DYNAMIC ANALYSES

4.1 Design criteria

To aid the design teams of the contractors during the engineering phase of the structures,guidelines have been prepared and provided by the HSL-Zuid Project-organization. These

guidelines are based on national and European standards anno 1999, such as ENV 1991-3:1995, supplemented with available research data and experiences with high-speed railwaysabroad. In guideline HSL600E, titled “Loads and Deformations of Structures”, the criteria withregard to the dynamic behavior of structures are stipulated. These can be summarized asfollows:

1. The vertical accelerations in the structure, as calculated in the center of the track, shall

not exceed 0.50g in case of ballastless track, for frequencies ranging from 0 to 20 Hz.This is a way to ensure that the structural accelerations will not negatively affect the passing train (rebound) and is introduced as a safety measure against derailment. Itdoes not mean in any way that acceleration signals outside the mentioned frequencyrange do not matter or may be ignored in the structural analyses.

2. To account for the dynamic response of a structure a dynamic coefficient ɸ2 is

introduced based on the determinant length (Lɸ) of the structure at hand. The value ofthis coefficient ranges from 1.00 to 1.67, as applicable for carefully maintained track.

By means of dynamic analysis a second coefficient ɸr has to be established, equal tothe quotient of the dynamic and static bending moments at any governing location in

the structure. The maximum of these coefficient ɸ2 and ɸr is then used as the generalmultiplier ɸ applicable to the load models (LM 71, SW/0 & /2) used for staticanalyses.

3. In order to ensure a proper level of passenger comfort, the vertical acceleration of thetrain is limited to a maximum of 1.0 m/s2 (classification: very good). However, thenatural frequency of the bridge across the Hollandsch Diep lies close to 1.0 Hz, whichis near the range of natural rigid car body frequencies of most trains (0.6 to 2.0 Hz).

Therefore an additional criterion has been introduced in the form of a weighted levelof “incomfort” of harmonic vibration (LIh) which may not exceed the value of45 [ms

5/3].

The limiting value of 45 is time dependent with a maximum duration of passage of15 s.

Derived from ERRI D190 (“Permissible deflection of steel and composite bridges forvelocities V > 160 km/h”, December 1995) this criterion is based on empirical data, as

shown in the following figure.


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0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

P a s s e n g e r ( i n - ) c o m f o r t [ % ]

LIh value

100% Satisfied

100% Unsatisfied

the in-betweens

LIh limit value (45)

Figure 7: Empirical data, source for the LIh comfort criterion as per ERRI D190

Taking into account a weighting factor of 0.40, the formulae for the LIh-value reads:

( ) 451.433

1

0

3≤⎥⎦

⎤⎢⎣⎡= ∫

T

vh dt t a LI (1)

where av(t) = the train acceleration; and T = the duration of passage.

These (3) design criteria do only indirectly apply to the track system. In the requirementsconcerning the track system it is stated that the application of the track system shall have nonegative effect on the behavior of the supporting structures, or in other words, have no negativeimpact on the results of the dynamic analyses already performed on these structures.

In the matter of passenger comfort, the criterion differs from that of the structures as it morespecifically includes the roughness effects of the rails, by means of actual field data. Asstipulated in UIC513 (Full Method), the level of comfort is to be determined by means of fieldmeasurements of accelerations at floor and seat level. A typical measurement period is 5minutes in which data is collected every 5 seconds, resulting in a total of 60 measurements per

period. Measurements are to be taken at the maximum operation velocity, 300 km/h in this project, and in all three (x:y:z) axis, resulting in one measurement every 417 m. Data is

processed, filtered and weighted into 50% and 95% probability ranges. The required comfortlevel of maximum 2 is applicable to both seated [NVA] and standing [NVD] positions, as perfollowing formulas:

( ) ( ) ( ) ( ) 2424 952

95

2

9595 ≤+++= cbd bW

XD

W

ZA

W

YA

W

ZP VA aaaa N (2)

( ) ( ) ( ) ( ) 254163 952

50

2

50

2

50 ≤+++= d d d d W

YP

W

ZP

W

YP

W

XP VD aaaa N (3)


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Structural damping is an important factor in the dynamic analyses. For the bridge structure adamping ratio of 0.010 was applied as per guideline HSL600E. For the rails and rail-fasteningsdamping ratios of 0.005 and 0.100 respectively were taken into account.

5.2 Vertical rail level geometry considerations

The dynamic analyses for the bridge across the Hollandsch Diep were performed twice. The purpose of the first round of analyses (2001) was to establish the structural integrity of the bridge and the level of passenger comfort with regard to the applicable design criteria. Staticanalyses revealed that temperature fluctuations and creep of the concrete deck will cause adeformation of the vertical alignment of the bridge (deck) and consequently the rail levelgeometry. As a result the level of passenger comfort will be compromised. This systematic

deformation [SD] in great lines follows the bridge’s natural deflection pattern under dead load,causing disturbing frequencies of 0.79 Hz at a train velocity of 300 km/h to 0.87 Hz at 330km/h (main span = 105.0 m). Not only do these frequencies come close to the bridge’s naturalfrequency of 1.10 Hz, they also fall within the range of frequencies, 0.80 to 1.20 Hz, to beconsidered for the real trains. Therefore, resonant effects are likely to occur. The maximumdifferential systematic deformation was established at 5 mm comprising of 3 mm at mid-spanand 2 mm at the center of the hammer-pieces. In the case the deformation at mid-span isupward directed (positive) the most favorable situation [SDR, with R = Reversed] is derived as

the train is ‘flattening’ its way across the bridge deck. Unfortunately, the opposite situationmay also occur. As a solution to this problem a corrective deflection [CD] or pre-camber of therail level was suggested by the design team of the bridge structure and incorporated by Rheda2000 vof. See figures 10 and 11. This pre-camber is defined as follows:

( ) ⎟⎟ ⎠ ⎞

⎜⎜⎝ ⎛

⎟⎟ ⎠ ⎞

⎜⎜⎝ ⎛ π−δ=δ

i

ini L

aa 2cos1

where δini = + 1.5 mm and Li = 70.0 m for the end-spans and = 105.0 m between piers anda = the distance along the bridge deck/track

0

15

30

45

60

75

90

105

-10.0 -7.5 -5.0 -2.5 0.0 2.5 5.0 7.5 10.0 12.5 15.0

L

I h v a l u e

(Differential) Systema tic Deforma tion of Bridge Deck / Ra ils [mm ]

V = 330 km/h

V = 300 km/h

V = 270 km/h

LIh limit value (45)

Figure 10: The effect of systematic deformation of the rails on passenger comfort


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105.0 m (total of 10 spans)

Pier Abutment

70.0 m

Pier Pier

+ 2 mm

- 3 mm

60.0 m

105.0 m (total of 10 spans)

47.5 m

70.0 m+ 3 mm

- 2 mm

Abutment

45.0 m

Pier Pier Pier

105.0 m (total of 10 spans)70.0 m+ 3 mm

Abutment Pier Pier Pier

Systematic Deformation

Systematic Deformation (Reversed)

Corrective Deflection / Pre-camber

Figure 11 : Systematic deformation and required corrective deflection or pre-camber

A second round of analyses was performed 2 years later in 2003, as part of the scope ofInfraspeed, to analyze the possible effects of the Rheda 2000® slab track system on the bridgestructure and to establish the final requirements with regard to the vertical rail level geometry.

The effect of rail roughness has been incorporated in more detail by combining actual fielddata for short wavelengths, ranging from 3 to 25 m, with theoretical data for long wavelengths

in excess of 25 m (source: prof. C. Esveld, TU Delft). By use of a scaling factor it is possible toalter the contribution of the long wavelengths to get in compliance with the required comfortlevel (see paragraph 4.1). However, deviations from the starting value of 1.00 will have animpact on the level of accuracy required during the final preparation of the vertical rail leveland possibly requires a closer monitoring of this level while the track is in operation.

Note that during the first dynamic analyses of the bridge, rail roughness effects were assumed

to be negligible due to the longs spans of the bridge, which resulted in a roughness factor equalto 1.00 according to formulae:

100

2

28.01φ−

+= L

roughness e f

where Lɸ = the span of the bridge with a minimum of 42.5 m (at both ends)

In order to comply, the scaling factor for the bridge across the Hollandsch Diep had to bereduced to 0.55 (see figure 12). For all other HSL-structures, analyzed for their interaction withthe Rheda 2000

® track system, scaling factors were found to be within a range of 0.92 to 1.12.

This meant that the preparation of the vertical rail level on the bridge would require moreattention and accuracy than at other structures, which was to be expected as this bridgestructure was and still is the most comfort sensitive structure in the entire HSL-Zuid project.


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The effect of rail roughness on the structural acceleration of the bridge deck remains small. At peak values an increase of approximately 10% is found compared to a situation with a perfectalignment of the rail level. See figure 14. With a maximum value of 0.40 m/s2 or 0.04g,obtained for the ICE3M2 train at 330 km/h, the criterion not to exceed 0.50g is easily fulfilled.

Maximum results for the THALYS2 and ICMAT trains were established at 0.26 and 0.20 m/s2

at corresponding velocities of 240 and 220 km/h. The impact of train types THALYS1 and

ICE3M1 proved to be smaller than for their double-sized companions.

Due to the low natural frequency of the bridge structure (1.10 Hz), filtering the structuralacceleration signal for frequencies between 0 and 20 Hz did not result in any reduction of theseaccelerations. With regard to the magnitude of the structural accelerations it could also be

concluded that the dynamic coefficient ɸr , part of the 2nd

dynamic criterion (see paragraph

4.1), would not exceed the value of 1.00 and would therefore not become governing. This can be verified considering the following. The distributed load of the real train ICE3M is 21.9kN/m. During its presence on the bridge the structure shows a response of maximum 0.04times its dead load which results to 11.0 kN/m (= 0.04 × 275 kN/m). Train load and structuralresponse combined amounts to 32.9 kN/m, which is considerably less than the uniform

distribution load of 80.0 kN/m belonging to Load Model 71 which is used in the static

analyses. In general terms, the dynamic coefficient ɸr results to 0.41 ( = 32.9 / 80.0), thus lessthan 1.00. This approach however is only valid for structures with large spans and a high ratioof dead load versus live load. For smaller structures, such as viaducts the dynamic analyses

showed higher ɸr -values, however hardly ever exceeding 1.67, the upper bound value for

coefficientɸ2.

-0.450

-0.400

-0.350

-0.300

-0.250

-0.200

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1100.0

B r i d g e d e c k a c c e l e r a t i o n s [ m / s 2 ]

Location [m]

ICE3M2 a t 330 km/h [SDCD] ICE3M2 at 330 km/u [SDCDRGF055]

Figure 14: Governing vertical structural accelerations in the bridge deck

Comparing both criteria with regard to the level of passenger comfort, the results show a strongsimilarity between the LIh- and RMS-values, which is obvious as they are based on the same principles. In the case of the bridge across the Hollandsch Diep the ratio LIh over


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corresponding RMS-value results to 111, i.e. for a RMS-value of 0.525 m/s2 the correspondingLIh-value = 58.3. See also figure 15.

In the worst case scenario, combining systematic deformation and corrective deflection or pre-

camber [SDCD] a maximum LIh-value of 52 is derived. According to figure 7, the number of100% satisfied passengers would reduce from 84% to 78%, while the number of 100%

unsatisfied passengers almost remains steady at 10%. Due to the fact that the conditions forwhich the maximum calculated systematic deformations occur are rare, the level of passengercomfort is only compromised for short periods of time and then only in certain areas of thetrain as can be seen in figure 16. Most of these areas coincide with the axle positions of thelocomotive sections. As a consequence of these arguments, the increase of the LIh-value from45 to 52 has been acknowledged by the HSL-Zuid Project-organization.

When both approaches for the level of passenger comfort are being compared, it could beconcluded that the criteria for the structure are more strict than those applicable to the tracksystem. However, the effects of vertical rail imperfections or rail roughness (short and longwavelengths) have not been taken into account during the first dynamic analyses concerningthe structure as they were nullified by the definition of the roughness factor. The RMS-rangefrom 0.470 m/s2, corresponding with a LIh-value of 52, to 0.525 m/s

2 is used to allow for a,however reduced (scaling factor = 0.55), realistic vertical rail level geometry in the Rheda2000® track system analyses.

As a result of the first dynamic analyses performed on the bridge across the Hollandsch Diepan alternative for the LIh-criterion was introduced in the way of a maximum allowable verticaltrain acceleration of 0.70 m/s2 valid for structures with 3 or more repetitive spans in a row. Thevalue of 0.70 m/s2 coincides with a LIh-value of 45 ms

-5/3 and takes out the dependency on the

duration of passage in the LIh approach.

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

60.0

65.0

70.0

75.0

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.500

0.550

0.600

0.650

0.700

16 0. 0 17 0. 0 18 0. 0 1 90. 0 2 00 .0 2 10 .0 22 0. 0 2 30 .0 2 40 .0 25 0. 0 26 0. 0 27 0. 0 2 80 .0 2 90 .0 3 00 .0 31 0. 0 32 0. 0 33 0. 0

L I h v a l u e s

M a x i m u m R M S t r a i n a c c e l e r a t i o n s [ m / s 2 ]

Train velocity [km/h]

[PA] [RMS] [CD] [RMS]

[SDCD] [RMS] [CDRGF055] [RMS]

[SDCDRGF055] [RMS] Upper Limit RMS-value

[PA] [LIh] [CD] [LIh]

[SDCD] [LIh] [CDRGF055] [LIh]

[SDCDRGF055] [LIh] Upper Limit LIh-value

Legend: [PA] : Perfect Alignment of the rails

[SD] : Systematic Deformation of the bridge deck due to temperature and creep effects

[CD] : Corrective Deflection or pre-camber of the rail level

[RGF055] : vertical Rail level Geometry with scaling factor of 0.55 for long wavelengths

Figure 15: Maximum RMS train accelerations and LIh-values for governing train type ICE3M2


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uplifting support forces to 50-60% of the support forces due to the dead load of the system,which is 30 kN per support. This results in a minimum safety factor against uplift of 1.67.

Having adapted the design of the transition slab with the restriction of uplifting forces at the

supports in mind has also been beneficial to the requirements with regard to the dynamiccoefficients, the level of passenger comfort and the forces in the rail-fastenings as they do not

reveal anything out of the ordinary. The dynamic bending moments in the transition slabremain below the static bending moments derived during the passage of static load models

LM71 and SW2. This results in a dynamic coefficient ɸr below unity. Due to its short

determinant length [Lɸ] coefficient ɸ2 is governing with a value of 1.67. The upward dynamicresponse of the steel plate is compensated by its dead weight. In a conservative approach of the passenger comfort, the governing RMS-value of the vertical train accelerations is established at

0.290 m/s2

, hence below the maximum allowable value of 0.525 m/s2

. The dynamicamplification factor of the forces in the rail fastenings does not exceed 1.40.

In figure 22, the time-history results for the support forces are shown during the passage oftrain type ICE3M2 at a velocity of 290 km/h, with a support stiffness of 500 MN/m and a

damping ratio of 0.050. The characteristics of the train, axle positions and loading effects (2times 8 wagons with 4 axles each) are clearly recognizable.

-70.0

-60.0

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500 5.000 5.500

S u p p o r t F o r c e s [ k

N ]

Time [s]

Figure 22: Time-history of support forces during passage of ICE3M(2) at 290 km/h

Out of the ordinary structures, especially small sized structures such as these transition slabs,combining a lot of different functions on a concentrated area, often require more attention than

usual and may create more questions than answers.

The basic design principle of these transition slabs had already been applied and proven itself

before in HSR tracks abroad. New, however were the operational train velocity, the traincharacteristics and the depth of the dynamic analyses. Coming up with a workable solution proved to be an interesting engineering challenge.


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for a better approach of the rail roughness impact in the design of the track system. However,for the sake of clarity both criteria should merge into one.

The transition slab is a structural element with a relative high natural frequency. Sliding over

the 4 supports but not vertically fixated the main problem here lies in the possible loss ofcontact which is not beneficial to the fatigue strength of the supports. By increasing the

stiffness over mass ratio and establishing the damping properties of the sliding PE-elements inthe supports, the (filtered) structural accelerations of the transition slab and the uplift forces inthe supports are kept within acceptable limits.

Figure 24: Rheda 2000 slab track system on bridge across the Hollandsch Diep(Photo, courtesy of Mr. P. Meijvis, DMC bv, The Netherlands)

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