Considerations for Development-High-Speed Rail Bridge Design Standards

8/18/2019 Considerations for Development-High-Speed Rail Bridge Design Standards

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CONSIDERATIONS FOR DEVELOPMENT OF

HIGH SPEED RAIL BRIDGE DESIGN STANDARDS

Y. Edward Zhou

URS Corporation

4 North Park DriveHunt Valley, Maryland 21030

Telephone: 301-820-3539

Fax: 301-820-3009

Email: [email protected]

Suoting HuChina Academy of Railway Sciences

No. 2 Daliushu Road, Haidian District

Beijing, China 100081


Zaitian KeChina Academy of Railway Sciences

No. 2 Daliushu Road, Haidian District


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ABSTRACT

Compared with conventional railways, high speed rail (HSR) has stricter requirements on bridge

structural stiffness to minimize deformations and avoid excessive vibrations or resonance due to

train crossings at high speeds. Bridge design for HSR requires a good understanding of train-

track-structure dynamic interactions, requirements for deflections, rotations, and natural

frequencies of bridge spans, as well as continuous welded rail (CWR)-structure interactions. A

review of China’s recent developments in HSR can benefit the development of HSR bridge

design standards in North America. In China, commercial operation of passenger trains up to 250

km/h (155 mph) began in 2007 on existing rail lines that serve mixed passenger and freight trains.

After 2007, construction of commercial passenger dedicated lines (PDL’s) started since further

upgrading of mixed-traffic rail lines for higher speeds was considered unpractical and

uneconomical. China released its Code for Design of High Speed Railway in late 2009 for

passenger train design speed between 250 km/h (155 mph) and 350 km/h (217 mph). The

Chinese HSR code is based on the UIC (International Union of Railways) code with adjustments


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INTRODUCTION

UIC (International Union of Railways) defines high speed rail (HSR) as systems of infrastructure

and rolling stock which operate at speeds of 250 km/h (155 mph) or higher on specially built

new lines, or the order of 200 km/h (124 mph) on specially upgraded existing lines (1). It is

commonly recognized that the first modern commercial HSR was Japan’s Shinkansen between

Tokyo and Osaka, which started operation in 1964 with a top speed of 256 km/h (159 mph). In

Europe, regular HSR services started in the 1970’s in France, Italy, Germany, Spain, and the

Great Britain.

China began research and planning on high speed rail (HSR) feasibility and technologies

in early 1990’s. A long debate was held over the type of technology to be employed for large

scale application: conventional rail vs. magnetic levitation (maglev). Finally in 2006, the

government decided to adopt the conventional wheel-rail technology for China’s HSR network.

Nevertheless the 30 km (18.6 mi) long Shanghai Maglev Demonstration Operation Line began

public service in January 2004 with a top operational speed of 431 km/h (268 mph) making it


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dedicated lines (PDL’s) started after 2007 since further upgrading of mixed-traffic rail lines for

higher speeds was considered unpractical and uneconomical.

China's HSR network consists of upgraded conventional rail lines and newly-constructed

PDL’s. As of June 2011, China has the world's largest in-service HSR network totaling

approximately 9,700 km (6,027 miles), including approximately 3,500 km (2,175 miles) with top

speed of 300 km/h (186 mph) or 350 km/h (217 mph). The best-known section of PDL is the

Beijing-Shanghai High Speed Railway that opened to the public in June 2011 with a design top

speed of 380 km/h (236 mph). The Chinese made CRH380 train-sets operate on this line.

Bridges account for approximately half of the total length on China’s PDL’s. Prior to

opening a line for service, the bridges are usually tested with a special train at a range of speeds

up to 110% of the design speed. The primary purpose of the test is to verify the traction and

power system and collect wheel-rail interaction data. Acceleration data is often collected from

these tests for characterizing the fundamental dynamic behavior of bridges.


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In addition, HSR lines require smoother geometrical alignment for horizontal curves and vertical

profiles to ensure safe and comfortable operation of trains traveling at high speeds.

HSR BRIDGE DESIGN CODES

UIC Code Leaflet 776-2 Design requirements for rail-bridges based on interaction phenomena

between train, track and bridge (2) provides HSR bridge design requirements specifically for

serviceability limit states concerning deformation and vibration. The UIC Code has other leaflets

that contain provisions for HSR bridge design, including Leaflet 776-1 Loads to be considered in

railway bridge design (3) and Leaflet 774-3 Track/bridge Interaction Recommendations for

calculations (4). European standards BS EN 1990:2002 Eurocode – Basis of Structural Design

(5) establishes principles and requirements for structural design and is intended to be used in

conjunction with EN 1991 to EN 1999 for the design of various types of civil structures. For

example, BS EN 1991-2:2003 Eurocode 1: Actions on structures – Part 2: Traffic loads on

b id defines loads and their dynamic effects for road pedestrian and railway bridges (6)


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HSR TRACK ALIGNMENT REQUIREMENTS

For track horizontal curves, the Chinese HSR code provides radius requirements for different

design speeds in the form of: “recommended radius”, “minimum radius – general”, “minimum

radius – special” (requiring technical and economical comparison as well as approval by the

Ministry of Railway), and “maximum radius”. Table 1 lists the Chinese HSR horizontal curve

radius requirements for main lines for different design speeds in Metric and US Customary units.

Also provided in the table are the degrees of curve corresponding to the radius requirements. The

Chinese HSR Code also has detailed requirements for horizontal transition spirals.

TABLE 1. Main Line Horizontal Curve Radius and Degree Requirements from Chinese HSR

Design Code.

350/250 km/h 300/200 km/h 250/200 km/h 250/160 km/h

(217/155 mph) (186/124 mph) (155/124 mph) (155/99 mph)Radius (m) 8,000 - 10,000 m 6,000 - 8,000 m 4,500 - 7,000 m 4,500 - 7,000 m

Radius (ft) 26,247 - 32,808 ft 19,685 - 26,247 ft 14,764 - 22,966 ft 14,764 - 22,966 ft

Degrees 0.22 - 0.17 deg. 0.29 - 0.22 deg. 0.39 - 0.25 deg. 0.39 - 0.25 deg.

Recomm'd

Track Type \ Design Speed


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For main line track vertical profiles, the Chinese HSR code specifies a maximum gradient of 20‰

(2%) in normal condition and 30‰ (3%) in difficult condition pending technical and economical

comparisons. In sections that are for trainsets made of motorized cars, the maximum allowed

gradient is 35‰ (3.5%). The Chinese HSR Code also has detailed requirements for gradient

changes and vertical curves.

OVERVIEW OF CHINA’S HSR BRIDGE DESIGN STANDARDS

The Chinese HSR bridge design specifications are similar to UIC’s with adjustments made for

specific situations in China based on results of analytical and field experimental research

conducted in the past two decades. In the Chinese Code for Design of High Speed Railway (7 ),

Chapter 7 Bridges and Culverts consists of the following sections:

7.1 General provisions

7.2 Design loads

7 3 Limits for structural deformations displacements and natural frequencies


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TABLE 2. Design Loads for Bridges and Culverts.

Loading Description

Selfweight of strutural components and auxiliary facilities

Prestressing forces

Effects of concrete shrinkage and creep

Earth pressure

Static water pressure and buoyancyEffects of foundation movements

Vertical train static live loads

Vertical highway static live loads (as applicable)

Vertical dynamic impact of train loads

Longitudinal and flexural interaction forces with CWR

Centrifugal forces

Lateral oscillation forcesTrain live load induced earth pressure

Pedestrian and railing loads

Aerodynamic loads

Train traction and braking forces

Wind loads

Flow pressure

Ice pressure

Effects of temperature changes

Freezing expansion pressure

Train derailment load

Loading Types

Permanent

Transient

Primary

loads

Secondary loads


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FIGURE 1. China HSR ZK Standard Live Load.

FIGURE 2. China HSR ZK Special Live Load.

Train load vertical dynamic impact for bridge structures is specified as (1 + µ), where


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continuous superstructures of three or more spans, the limits in Table 3 are to be multiplied by a

factor of 1.1. For continuous or simply spans of two or less, the limits in Table 3 are to be

factored by 1.4. For single-track simple or continuous spans, the limits in Table 3 are to be

factored by 0.6.

TABLE 3. Vertical Deflection Limits for Double-Track Simple-Span Concrete Girders of Span

Lengths less than 96 m (315 ft).

For arch and rigid frame bridges, structural deflections must also take into consideration

of temperature effects, in addition to live load actions. For prestressed concrete bridges, creep

i d d id l d f ti l t b t k i t t

L ≤ 40 (131) 40 (131) < L ≤ 80 (262) L > 80 (262)250 (155) L/1,400 L/1,400 L/1,000

300 (186) L/1,500 L/1,600 L/1,100

350 (217) L/1,600 L/1,900 L/1,500

Design Speed

km/h (mph)

Span Length Range, m (ft)


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For girder ends at piers, the rotation (θ1 or θ2) of each girder end needs to satisfy the limit

for the girder end at abutment (θ) in addition to the requirements for the sum of girder end

rotations in adjacent spans (θ1 + θ2).

TABLE 4. Limits for Vertical Girder End Rotations.

Requirements for Vertical Natural Frequencies of Girders

Requirements for dynamic characteristics of bridge spans are established based upon criteria in

consideration of dynamic responses of the structure, safety of crossing trains, as well as ride

Track Type Location Limit (rad) Girder End Cantilever, Lc, m (ft)

between abutment and span θ ≤ 2.0‰

between adjacent spans θ1 + θ2 ≤ 4.0‰

θ ≤ 1.5‰ Lc ≤ 0.55 m (1.80 ft)

θ ≤ 1.0‰ 0.55 (1.80) < Lc ≤ 0.75 (2.46)

θ1 + θ2 ≤ 3.0‰ Lc ≤ 0.55 m (1.80 ft)θ1 + θ2 ≤ 2.0‰ 0.55 (1.80) < Lc ≤ 0.75 (2.46)

Ballastless

between abutment and span

between adjacent spans

Ballasted


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TABLE 5. Vertical Vibration Natural Frequency Lower Limits for Double-Track Simple-Span

Concrete Box Girders of Common Lengths Not Requiring Dynamic Analysis.

For bridges that are beyond the coverage of Table 5, dynamic analysis for train-structure

coupling vibrational responses is required based on the actual condition of train crossing and a

maximum train speed of 1.2 times the design speed. The following requirements must be

satisfied :

Wheel-climb derailment factor: Q/P ≤ 0.8

A l i h d i i ∆P/P 0 6

250 (155) 300 (186) 350 (217)12 (39) 100/L 100/L 120/L

16 (52) 100/L 100/L 120/L

20 (66) 100/L 100/L 120/L

24 (79) 100/L 120/L 140/L

32 (105) 120/L 130/L 150/L

Design Speed, km/h (mph)Span Length

m (ft)


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where, Q = lateral wheel load on rail, kN (1 kN = 225 lbs force); P = vertical axle load, kN; P0 =

static axle weight, kN; ∆P = reduction of vertical axle load due to dynamic action; g = standard

gravity = 9.81 m/s2 (32.174 ft/s

2 ).

Requirements for Longitudinal Stiffness of Piers and Abutments

For simple-span concrete girders located in the fixed zone (no longitudinal rail movements due

to temperature) of ballasted continuous-welded-rail (CWR) track, longitudinal stiffness at the top

of piers and abutments must be no lower than the limits listed in Table 6 (7 ).

TABLE 6. Longitudinal Stiffness Limits for Top of Piers and Abutments.

Double-Track Single-Track

≤ 12 (39) 100 (57) 60 (34)

16 (52) 160 (91) 100 (57)

20 (66) 190 (108) 120 (69)

24 (79) 270 (154) 170 (97)

TypeSpan

m (ft)

Min. Longitudinal Stiffness, kN/cm (kip/in)

Pier


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Girder Vibration Frequency Requirements

Crossing trains act as vibration excitation sources to bridge girders. The excitation frequency

varies with train speed. As the excitation frequency approaches the natural frequencies of the

structure excessive vibrations or even resonance may occur. These dynamic responses can cause

damages to the track system and the structure, or even threaten the safety of the crossing train or

the bridge. Factors affecting train-bridge dynamic responses include natural frequencies of the

girder, damping ratio of the structural system, train speed, car length and truck spacing, track

irregularities, flat wheels, etc.

Previous research suggested that the primary factors affecting the vertical excitation

frequency of train loading are the train speed and car length. The effects of other factors such as

the axle spacing and truck spacing are secondary because their repeated actions are not

continuous. Thus the excitation frequency is simply:


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(a) 32 m (105 ft) Box Girders (b) 24 m (79 ft) Box Girders

FIGURE 4. Field Measured Correlation between Vertical Excitation Frequency and Train Speed.

UIC’s requirements for bridge girder natural frequencies consist of the upper bound and

lower bound for varying span lengths. The lower bound is to control excessive vibration or

resonance due to train crossings; and the upper bound is to limit train-track dynamic responses

due to track irregularities. For bridge girders of natural frequencies within the required envelope

stipulated in design specifications, structural design can be based on the static design loads


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high magnitudes of these lower limits for actual girders and the low magnitudes of track

irregularities permitted by inspection requirements.

Figure 5 shows comparisons between computed and field measured dynamic impact for

32 m (105 ft) simple-span concrete box girders due to the CRH2 train sets (8 ). The figure clearly

demonstrates that girders not satisfying the natural frequency requirements in Table 5 (≥130/L at

300 km/h, ≥150/L at 350 km/h) can be subject to excessive dynamic response or resonance at

train speeds higher than 300 km/h (186 mph).

D y n a m

i c I m p a c t ( 1 + µ )

Computed (natural freq. = 150/L)

Computed (natural freq. = 120/L)

Field Measured (loaded trains)

Field Measured (empty trains)


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ft/s2), for varying train speed. However, different countries use different live loads for the

calculation of maximum girder deflection (δ) for double-track bridges. For example, UIC uses

single-track design live load with dynamic impact; Japan uses single-track operating live load

including dynamic impact; China uses the standard ZK design live load on both tracks but not

including dynamic impact.

Comprehensive comparative studies were made in China for varying span lengths

considering factors such as single-track vs. two-track loading, variation of design live load

among different countries, tolerances for track irregularities, etc. Figure 6 depicts computer

models used for calculating static and dynamic responses of concrete box girders to crossing

train loads. Such research yielded Table 3 as the result.


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girder end rotation imposes push-down and uplift forces, respectively, to the rail on either side of

the gap between the girder ends. These forces may cause damages to the ballast, rail fasteners, or

the slab system if not controlled properly. Research in China suggested limits for vertical girder

end rotations (9), as summarized in Table 4, for ensuring proper performance of the rail-fastener-

slab system, reducing maintenance needs, and ensuring the safety of crossing trains at high

speeds.

FIGURE 7. Illustration of Bridge Girder End Rotation and Impact to Rail-Fastener-Slab System.

CWR-Structure Interactions

扣件

梁梁

钢轨

Girder Girder

Rail

Fastener


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etc. (10). The results from such research have provided great value and detailed provisions to

proper design of bridges and track systems for HSR.

Distribution of train braking forces among bridge substructure depends on the

longitudinal stiffness of adjacent bridge piers and abutments. Research in China suggested that

the longitudinal stiffness of bridge substructure is an important design parameter; and Table 6

was developed as a result to provide longitudinal stiffness limits for the top of piers and

abutments in the fixed zone of ballasted CWR. Since the braking force only considers one train

for double-track bridges in the Chinese bridge design standards, values in Table 6 are to be

multiplied by a factor of 2.0 for piers and abutments supporting elevated train stations within the

departing and approaching limits to consider the simultaneous occurrence of traction and braking

forces on both tracks.

CONCLUSIONS

High speed rail (HSR) has strict requirements on bridge structural stiffness to minimize


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km/h (217 mph). Much of their research results and bridge design standards can be used as a

good resource for the development of HSR bridge design standards in North America.

REFERENCES

(1) UIC (International Union of Railways), General definitions of highspeed

http://www.uic.org/spip.php?article971, retrieved June 2012

(2) UIC (International Union of Railways), Leaflet 776-2, Design requirements for rail-

bridges based on interaction phenomena between train, track and bridge, 2nd

edition, June

2009

(3) UIC (International Union of Railways), Leaflet 776-1 Loads to be considered in railway

bridge design, 5th edition, August 2006

(4) UIC (International Union of Railways), Leaflet 774-3 Track/bridge Interaction

Recommendations for calculations, 2nd

edition, October 2001

(5) BSI (British Standards Institution) / CEN (European Committee for Standardization) BS


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Proceedings of 60th Anniversary Symposium of China Academy of Railway Sciences,

China Railway Press, Beijing, 2010

(9) Niu, B., Hu, S., Wei, F., Ma, L., Research and Applications of Prestressed Concrete Box

Girders in China’s High Speed Railway (in Chinese), Proceedings of 19th

China Bridge

Engineering Conference, Shanghai, 2010

(10) Lu, Y., Research and Application of Continuous Welded Rail Track (in Chinese), China

Railway Press, 2004

LIST OF TABLES

TABLE 1. Main Line Horizontal Curve Radius and Degree Requirements from Chinese HSR

Design Code.

TABLE 2. Design Loads for Bridges and Culverts.

TABLE 3. Vertical Deflection Limits for Double-Track Simple-Span Concrete Girders of Span

Lengths less than 96 m (315 ft).


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FIGURE 5. Comparison between Computed and Field Measured Dynamic Impact for 32 m (105 ft)

Simple-Span Concrete Box Girders.

FIGURE 6. Computer Models for Dynamic Responses of Concrete Box Girders.

FIGURE 7. Illustration of Bridge Girder End Rotation and Impact to Rail-Fastener-Slab System.


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September 16-19, 2012 ! Chicago, IL

2012 Annual Conference & Exposition

Considerations for Development ofHigh Speed Rail (HSR)

Bridge Design Standards

Ed Zhou (1), Suoting Hu (2),Bin Niu (2), & Zaitian Ke (2)

(1) URS Corporation(2) China Academy of Railway Sciences (CARS)

© 2012 AREMA


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• UIC (International Union of Railways)’s HSR definition:systems of infrastructure and rolling stock which

operate at speeds of

– 155 mph (250 km/h) or higher on specially built new lines, or

– the order of 124 mph (200 km/h) on specially upgradedexisting lines

• First modern commercial HSR: Japan’s Shinkansen

between Tokyo and Osaka, which started operation in

1964 with a top speed of 159 mph (256 km/h ).• In Europe, regular HSR services started in the 1970’s in

France, Italy, Germany, Spain, and the Great Britain.

HSR – Definition & Major Milestones

© 2012 AREMA


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• UIC Code

– BS EN 1990:2002 Eurocode – Basis of Structural Design

– BS EN 1991-2:2003 Eurocode 1: Actions on structures – Part 2:Traffic loads on bridges

– Leaflet 776-1 Loads to be considered in railway bridge design

– Leaflet 776-2 Design requirements for rail-bridges based oninteraction phenomena between train, track and bridge

– Leaflet 774-3 Track/bridge Interaction Recommendations for

calculations

• Chinese Code

• Other…

HSR Bridge Design Codes

© 2012 AREMA


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China’s HSR Network for 11th 5-Year Plan (2006 ~ 2010)

© 2012 AREMA


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•

Early 1990’s: began research on feasibility andtechnologies.

• 1998 ~ 2006: debate on national HSR technology,

finally decided to adopt the conventional wheel-rail

track over maglev (magnetic levitation).

• 1999 ~ 2003: constructed a 251 mi. (404 km ) passengerdedicated line (Qin-Shen) of design and operating

speed of 124 ~ 155 mph (200 ~ 250 km/h), with top test

speed of 186 mph (300 km/h), serving as the national

research/testing/practice base for HSR technologies.• 2000 ~ 2004: constructed world’s first commercial HS

maglev in Shanghai, 19.0 mi. (30.5 km) long, 267 mph

(431 km/h) top speed, of German technology.

HSR Development History in China

© 2012 AREMA


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• 1997 ~ 2007: conducted six rounds of “speed-lift”campaigns on existing lines across the country,

increasing passenger train speed up to 124 – 155 mph

(200 – 250 km/h) on multiple existing rail lines that

served mixed passenger and freight trains.

•

2007 ~ : started developing commercial passengerdedicated lines (PDL), because further upgrading of

mixed-traffic rail lines for higher speeds (> 155 mph, or

250 km/h) was considered unpractical and

uneconomical.

•

By June 2011 (after opening of Beijing–Shanghai HSRline), in-service HSR mileage totaled ±6,027 miles (9,700

km), including ± 2,175 miles (3,500 km) of 186 ~ 217 mph

(300 ~ 350 km/h) top speed.

HSR Development History in China (cont’d)

© 2012 AREMA


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Development Process of China’s HSR: Four Stages

"# $%&'()*)+,

-&&./.*01)(

2# 3/4)51(+ 678+%91)(

:# -;9)5;8(+ 63/45)# 3(()


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•

First Chinese Code for Design ofHigh Speed Railway released onDec 1, 2009, for passenger trainsof design speed of 155 ~ 217mph (250 ~ 350 km/h).

•

Developed based on reviewingand learning from those of UIC(International Union of Railways),Germany, Japan, etc.

• Similar to UIC’s, with adjustments

for specific situations in Chinabased on results of analyticaland field experimental researchconducted in the past twodecades.

China HSR Design Standards (2009)

© 2012 AREMA


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•

22 Chapters: –

General Design Considerations

– Alignment

– Embankment and Track Bed

– Bridges and Culverts

–

Tunnels –

Tracks

– Stations

– Traction and Power Supply

– Communications

–

Signaling

– Rolling Stock Equipment

– Environmental Protection

– …

China HSR Design Standards (2009) (Cont’d)

© 2012 AREMA


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HSR Track Horizontal Curve Req’tsThree levels: (1) recommended, (2) minimum general, (3) minimum special that requires

technical and economical comparison and approval of the Ministry of Railway

350/250 km/h 300/200 km/h 250/200 km/h 250/160 km/h

(217/155 mph) (186/124 mph) (155/124 mph) (155/99 mph)

Radius (m) 8,000 ! 10,000 m 6,000 ! 8,000 m 4,500 ! 7,000 m 4,500 ! 7,000 m

Radius (ft) 26,247 ! 32,808 ft 19,685 ! 26,247 ft 14,764 ! 22,966 ft 14,764 ! 22,966 ft


Radius (m) 7,000 m 5,000 m 3,500 m 4,000 m

Radius (ft) 22,966 ft 16,404 ft 11,483 ft 13,123 ft

Degrees 0.25 deg. 0.35 deg. 0.50 deg. 0.44 deg.

Radius (m) 6,000 m 4,500 m 3,000 m 3,500 m



Radius (m) 8,000 ! 10,000 m 6,000 ! 8,000 m 4,500 ! 7,000 m 4,500 ! 7,000 m

Radius (ft) 26,247 ! 32,808 ft 19,685 ! 26,247 ft 14,764 ! 22,966 ft 14,764 ! 22,966 ft


Radius (m) 7,000 m 5,000 m 3,200 m 4,000 m

Radius (ft) 22,966 ft 16,404 ft 10,499 ft 13,123 ftDegrees 0.25 deg. 0.35 deg. 0.55 deg. 0.44 deg.

Radius (m) 5,500 m 4,000 m 2,800 m 3,500 m



Radius (m) 12,000 m 12,000 m 12,000 m 12,000 m



Ballastless

Track

Recomm'd

Min. Gen.

Min. Spec.

Maximum

Ballasted

Track

Recomm'd

Min. Gen.

Min. Spec.

Track Type \ Design Speed

© 2012 AREMA


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•

Chapter 7 Bridges and Culverts –

7.1 General provisions

– 7.2 Design loads

– 7.3 Limits for structural deformations, displacements and

natural frequencies

– 7.4 Structural analysis and construction details

– 7.5 Bridge deck arrangement and auxiliary facilities

– 7.6 Elevated station structures

– 7.7 Junctions to other structures and facilities

•

Design speed of 155 ~ 217 mph (250 ~ 350 km/h)• Primarily for standard PSC girder spans

• Steel structures are usually for unconventional longspans, which require special train-structure interactionanalysis.

Bridge Design

© 2012 AREMA


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Bridge Design LoadsLoading Description

Selfweight of strutural components and auxiliary facilities

Prestressing forces

Effects of concrete shrinkage and creep

Earth pressure

Static water pressure and buoyancy

Effects of foundation movements

Vertical train static live loads

Vertical highway static live loads (as applicable)

Vertical dynamic impact of train loads

Longitudinal and flexural interaction forces with CWR

Centrifugal forces

Lateral oscillation forces

Train live load induced earth pressure

Pedestrian and railing loads

Aerodynamic loads

Train traction and braking forces

Wind loads

Flow pressure

Ice pressure

Effects of temperature changes

Freezing expansion pressure

Train derailment load

Collision forces from ships and barges

Collision forces from automobiles

Construction loads

Earthquake loads

Rail-break forces from CWR (continuous-welded-rail)

Special loads

Loading Types

Permanent

Transient

Primary

loads

Secondary loads

© 2012 AREMA


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•

ZK standard live load

• ZK special live load

HSR Train Live Load

"# $%&'

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,23'

(42"4/01

# 5 4,, $%

(# 5 ##)+"4 -.1

62"'

(7247/01

# 5 47, $%

(# 5 7")4,4 -.1

"# $%&'

(#)*+, -.&/01

62"'

(7247/01

62"'

(7247/01

,23'

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62"'

(7247/01

62"'

(7247/01

62"'

(7247/01

© 2012 AREMA


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• Train load vertical dynamic impact for bridge structuresis specified as (1 +μ):

where Lφ = loading length in meters

– For simple spans, Lφ = span length

– For continuous spans of 2 " n " 5: Lφ = Lavg(1 + n/10)

– For continuous spans of more than five spans, Lφ = 1.5Lavg

Lavg = average span length

Train Load Vertical Dynamic Impact

© 2012 AREMA


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• Under ZK design live load without dynamic impact

• For continuous spans of # 3, multiplied by 1.1

• For continuous/simple spans " 2, multiplied by 1.4

•

For single-track simple/continuous spans, multiplied by 0.6• For arches and rigid frames, temperature effects also to be

considered.

• For PSC bridges, creep induced residual deformations also to beconsidered.

Girder Deflection Requirements

Vertical Deflection Limits for Double-track Simple-spanConcrete Girders of Span Lengths less than 315 ft (96 m)

L ! 131 (40) 131 (40) < L ! 262 (80) L > 262 (80)

155 (250) L/1,400 L/1,400 L/1,000

186 (300) L/1,500 L/1,600 L/1,100

217 (350) L/1,600 L/1,900 L/1,500

Design Speed

mph (km/h)

Span Length Range, ft (m)

© 2012 AREMA


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• Under ZK design live load without dynamic impact

• For girder ends at piers, rotation (θ1 orθ2) of each girder endneeds to satisfy the limits for abutments (θ) in addition to those forthe of adjacent spans (θ1 +θ2)

Girder End Rotation Requirements

Vertical Girder End Rotation Limits for Double-rack Simple-span Concrete Girders Shorter than 315 ft (96 m)

! !1 !2 !

!"#$%&'$ !"#$%&'$)*&+

Track Type Location Limit (rad) Girder End Cantilever, Lc, ft (m)

etween abutment and span ! " 2.0‰

between adjacent spans !1 + !2 " 4.0‰

! "

1.5‰ Lc"

1.80 ft (0.55 m)! " 1.0‰ 1.80 (0.55) < Lc " 2.46 (0.75)

!1 + !2 " 3.0‰ Lc " 1.80 ft (0.55 m)

!1 + !2 " 2.0‰ 1.80 (0.55) < Lc " 2.46 (0.75)

Ballasted

Ballastless

between abutment and

span

between adjacent spans

© 2012 AREMA


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• To ensure train safety and ride comfort at high speeds

• Based on comprehensive experimental & analytical

research considering single-track vs. two-track loading,

variation of design live load among different countries,

tolerances for track irregularities, etc., for varying spanlengths

Research on Girder Stiffness Requirements

© 2012 AREMA


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• UIC criteria developed primarily for train speeds below 250 km/h(155 mph), natural frequency lower limit (no) for simple-spanconcrete girders shorter than 96 m (315 ft):

Girder Vibration RequirementsVertical Natural Frequency Lower Limits for Double-Track Simple-Span

Concrete Box Girders of Common Lengths Not Requiring Dynamic Analysis

(L = span length in meters)

250 (155) 300 (186) 350 (217)

12 (39) 100/L 100/L 120/L16 (52) 100/L 100/L 120/L

20 (66) 100/L 100/L 120/L

24 (79) 100/L 120/L 140/L

32 (105) 120/L 130/L 150/L

Design Speed, km/h (mph)Span Length

m (ft)

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Requirements for case-specific train-structure dynamic analysis:

• Train speed up to 1.2 times design speed• Derailment factor (lateral/vertical wheel loads): Q/P " 0.8

•

Wheel load reduction ratio due to dynamic action:Δ

P/P "

0.6• Wheel lateral force (kN): Q " 10 + P0/3• Vertical acceleration of train body: a z " 0.13g (half-peak value)• Lateral acceleration of train body: ay " 0.10g (half-peak value)• Sperling ride comfort index: W " 2.50 excellent

2.50 < W " 2.75 good

2.75 < W " 3.00 acceptable• Bridge deck vertical acceleration (due to an excitation " 20 Hz):

" 0.35g for ballasted track" 0.50g for ballastless track

Requirements for Bridges Requiring Dynamic Analysis

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•

Crossing trains are vibration excitation sources to bridge girders.

• Train load excitation frequency: f exc. = V /Lv, (V =train speed, Lv=car length)

• Other factors, e.g., axle spacing, truck spacing, etc. are secondary.

• Bridge design aims to avoid girder natural frequencies close to f exc.

Research on Train Loading Excitation Frequency

,*&-. /&01#+&. 23++&-043' "&$5&&' 6&+470- 897*$043' ,+&:#&'7; 0'.


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• For bridge vibration control, UIC provides a girder natural frequencyenvelope consisting of a lower bound (for vertical train loads) and anupper bound (for track irregularities) for varying span lengths.

• Experience indicated that the UIC lower bound cannot eliminate

excessive vibration at train speeds above 155 mph (250 km/h).

• Chinese code raised the lower bound and eliminated the upper bound.

Research on Girder Vibration Frequency Requirements

23%>0+*13' "&$5&&' 23%>#$&. 0'. ,*&-. /&01#+&. ?;'0%*7 @%>07$ A3+ BC % DEFG HI

=*%>-&J=>0' 23'7+&$& K39 L*+.&+1

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• For areas within departing and approaching limits of

elevated stations, the stiffness limits are multiplied by afactor of 2.0

Longitudinal Stiffness Requirements for Piers & Abut.’s

M3'N*$#.*'0- =4O'&11 M*%*$1 A3+ 3A )*&+1 0'. !"#$%&'$1 A3+=*%>-&J1>0' 23'7+&$& L*+.&+1 *' ,*9&. P3'& 3A K0--01$&. 2QR

Double-Track Single-Track

! 12 (39) 100 (57) 60 (34)

16 (52) 160 (91) 100 (57)

20 (66) 190 (108) 120 (69)

24 (79) 270 (154) 170 (97)

32 (105) 350 (200) 220 (126)

40 (131) 550 (314) 340 (194)

48 (157) 720 (411) 450 (257)

Abutment 3,000 (1,713) 1,500 (857)

TypeSpan

m (ft)

Min. Longitudinal Stiffness, kN/cm (kip/in)

Pier

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• Large territory and immense railway track mileage

• Develop HSR via a transition process from existing railway

tracks that serve mixed passenger and freight trains.

• China is the only country that runs commercial train service

on conventional rail lines up to 217 mph (350 km/h ).

•

Much of their research results and bridge design standardscan be utilized as a good resource by AREMA.

China – U.S. Similarities in HSR Development

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September 16-19, 2012!

Chicago, IL


Questions?


Office phone: 301-820-3539

Documents

Considerations for Development-High-Speed Rail Bridge Design Standards