1 General Provisions
1.0.1 This Code is formulated with a view to implementing relevant laws and regulations and railway technical policies of the nation, unifying the technical standards of the design of railway bridges and culverts, and making the design of railway bridges and culverts meet the requirements of safety, reliability, advancedness, maturity, cost effectiveness, applicability and environmental protection.
1.0.2 This Code is applicable to the design of bridges and culverts on standard gauge high-speed railway, intercity railway, Class I and Class II mixed passenger and freight railway, and heavy-haul railway to be constructed or renovated.
1.0.3 Railway bridges and culverts shall meet the requirements of operation, inspection, maintenance and emergency repair, and shall have good durability. The structure of railway bridges and culverts shall be concise and aesthetic, and shall be standardized as much as possible to facilitate fabrication and mechanized construction.
1.0.4 The design service life of the main structure of railway bridges and culverts shall be 100 years.
1.0.5 The design scheme of railway bridges and culverts shall be based on the history, current conditions and trend of the river, and geological conditions, taking into consideration the interrelation between the bridge/culvert and the road, water conservation, navigation, industry and agriculture, and the requirements on environmental protection, soil and water conservation and cultural relic protection.
1.0.6 During fabrication, transportation, erection and operation, the structure of railway bridges and culverts shall have the specified strength, rigidness and stability. The structure of railway bridges and culverts shall meet the requirements of track regularity, train running safety and riding comfort.
1.0.7 The functions, hydrological and geological conditions, environmental conditions, track types, construction methods and other factors shall be considered in the selection of the structural types of railway bridges and culverts.
1.0.8 The construction materials for railway bridges and culverts shall be selected with consideration of the structure types, force conditions, operation requirements and environment conditions.
1.0.9 The design flood frequency and the check flood frequency of railway bridges and culverts shall be in accordance with Table 1.0.9.
Table 1.0.9 Flood Frequency Standard for Bridges and Culverts
Design flood frequency Cheek flood frequency
Bridge Culvert Very long bridge (or long bridge) featuring complex technology, difficulty in repaire or of great significance
1/100 1/100 1/300
Notes: 1 If the observed flood (including investigated flood) frequency is smaller than the design flood frequency listed in the above table, the observed flood frequency shall be adopted for the design. However, the design flood frequency for very long bridges, long bridges and medium bridges shall not be smaller than 1/300, and that for short bridges and culverts shall not be smaller than 1/100.
2 When the water level does not agree with the flow rate due to upwind, ice jam, tide, water intrusion, river-bed evolution, reservoir impoundment and backwater of other hydraulic structures, the flow rate and the water level shall be determined respectively.
3 For bridges and culverts within the inundation scope of reservoirs, the flood frequency listed in the above table shall be adopted For bridges and culverts downstream a dam, the standard flood discharge of the reservoir listed in the above table plus the quantity of the catchment between the bridge and the dam shall be used as the flow rate by which the above table bridge and culvert, relevant departments shall be negotiated with to improve the checking flood frequency standard of the dam to make it conform to the flood frequency standard of the railway bridges and culverts. If it is difficult to do so, the design can be performed according to the natural status of the stream, however, the unfavorable influence of the dam breaking on the bridges and culverts shall be considered.
4 For bridges and culverts within the upstream and downstream influence scopes of dams, the design flood frequency of the bridges and culverts may be increased appropriately if the sediment deposition of the reservoir is likely to have an unfavorable influence on the bridges and culverts.
5 The opening of the submerged culvert and/or inlet submerged culvert shall be checked according to the flood frequency of the design embankment height.
6 For the renovation of the existing railway line and/or the addition of the second railway line, the flood frequency shall be determined according to the operation conditions end the specific status of the flood hazard, and the existing buildings shall be utilized as much as possible.
1.0.10 The structure gauge of bridges and culverts shall comply with the requirements of relevant current standards.
1.0.11 The design of safety warning signs, protection signs and protection facilities of bridges and culverts shall comply with Safety Management Regulations of Railways (Decree No.639 of the State Council of the People's Republic of China).
1.0.12 Regarding the renovation of the existing railway line or the addition of the second railway line, the standard for the new railway line shall be adopted for railway sections to be added, while it should be adopted for railway sections to be renovated.
1.0.13 In addition to this Code, the design of railway bridges and culverts shall also comply with relevant current mandotary codes of the nation.
2 Terms and Symbols
2.1 Terms
2.1.1 High-speed railway (HSR)
a passenger dedicated line with a design speed of 250 km/h or higher (including reservation) and an initial operating speed of not less than 200 km/h
2.1.2 Intercity railway
a fast, convenient, and frequently-operating passenger dedicated line among neighboring cities or city groups with the maximum design speed of 200 km/h
2.1.3 Mixed passenger and freight railway
a railway where freight trains and passenger trains operate on the same track with the maximum design speed of 200 km/h
2.1.4 Heavy-haul railway
a railway which meets two of the following three conditions: 1) Traction mass being greater than 8 000 t; 2) Axle load being greater than 27 t; 3) Annual transport capacity on at least 150 km track being more than 40 million tons
2.1.5 Railway bridge
An overhead structure built to carry one railway line or more for striding over physical obstacles or over man-made facility
2.1.6 Railway culvert
a structure built to cross the railway subgrade and used for flood discharge or used for irrigation or used as a passageway.
2.1.7 Bridge span
distance between centers of two supports along the bridge.
2.1.8 Length of bridge
for girder bridges, it refers to the distance between breast walls of abutment; for arch bridges, it refers to the distance between the two expansion joints (between the end wall on the arch and the abutment) at both ends; for rigid frame bridges, it refers to the distance between two outer edges of the rigid frame along the span.
2.1.9 Very long bridge
a railway bridge more than 500 m long
2.1.10 Long bridge
a railway bridge whose length is between 100 m and 500 m
2.1.11 Medium bridge
a railway bridge whose length is between 20 m and 100 m
2.1.12 Short bridge
a railway bridge 20 m long or less
2.1.13 Pier
the structure supporting the adjacent bridge superstructure and transferring its load to the foundation
2.1.14 Abutment
the retaining structure connecting bridge superstructure with subgrade
2.1.15 Vertical dynamic factor of train
vertical dynamic effect of the running train on bridge or other structures
2.1.16 Centrifugal force of train
horizontal force towards outer side of curves generated during train running on curves
2.1.17 Braking force of train
horizontal force acting on structures towards the running direction which is generated when brakes are applied on the running train
2.1.18 Tractive force of train
horizontal force acting on structures opposite to the running direction when the train starts up
2.1.19 Lateral sway force of train
lateral swaying force acting on the rail surface during train running
2.1.20 Longitudinal force due to the thermal expansion of temperature variation
the longitudinal force generated from the longitudinal relative displacement of the bridge and long rail due to the thermal expansion of temperature variation
2.1.21 Longitudinal force due to the deflection of structure
the longitudinal force generated from the longitudinal relative displacement of the bridge and long rail due to the bridge deflection under the action of the train load
2.1.22 Longitudinal force due to the breaking of long rail
the longitudinal force generated from the longitudinal relative displacement of the bridge and long rail due to the fracture of long rail
2.1.23 Longitudinal force of long rail
a general term of above-mentioned longitudinal forces: due to the thermal expansion of temperature variation, due to the deflection of structure, and due to the breaking of long rail
2.1.24 Derailment factor(L/V ratio)
ratio between lateral and vertical forces applied on the rail by wheels
2.1.25 Natural frequency
vibration frequency determined by mass, rigidity, damping and boundary conditions of the bridge structure
2.1.26 Dynamic factor
ratio between dynamic response (dynamic deflection or stress) to static response (static deflection or stress), generated on structure during the running of train
2.1.27 Post-construction settlement
amount of settlement of the infrastructure after the completion of track laying
2.2 Symbols
2.2.1 External force and internal force
p——vertical earth pressure acting on the culvert by the embankment (kPa)
e——horizontal earth pressure acting on the culvert by the embankment, or horizontal earth pressure acting on the culvert by the live load (kPa)
qh——vertical pressure acting on the culvert by the live load (kPa)
ξ——earth pressure coefficient
K——earth pressure coefficient, or pier shape coefficient
1+μ——dynamic factor
W——wind load strength (Pa), ship weight or catamaran weight(kN), or vertical static live load of train (kN, kN/m)
W0——basic wind pressure (Pa)
P——flowing water pressure (kN)
F——collision force of ship or catamaran (kN)
q1——vertical pressure acting on circular culvert pipe by permanent load and live load (kPa)
q2——horizontal pressure acting on circular culvert pipe by permanent load and live load (kPa)
2.2.2 Geometric parameter
L——bridge span, or loading length of influence line (m)
f——arch rise (m)
Δ——horizontal displacement of top cap surface of pier and abutment (m)
r——average radius of circular pipe section (m)
3 Layout of Bridge and Culvert
3.1 General Requirements
3.1.1 Bridges and culverts shall not be located on arable lands or if no alternatives are available, shall minimize the use of arable land. The layout shall take into consideration of the requirements and influences of land and water transportation, irrigation and drainage, water source protection areas, wildlife reserves and underground pipelines. Siting of bridges and culverts shall be integral to well- functioning drainage systems together with natural water systems and local irrigation and drainage systems.
3.1.2 It is a principle to build one bridge when one river is to be crossed. It should not be forced to change the water courses or concentrated flow by long or large diversion dike.
3.1.3 Natural water courses should not be rechanneled. If the rechanneling of water course will surely be able to improve the working conditions of bridges and culverts or bring considerable economic benefits, it may be allowed to do so. Nevertheless, the consequences of the change on the hydraulic conditions shall be taken into consideration.
3.1.4 The centerline of bridge site should be orthogonal to the flow direction of floodwater. The backwater at the bridge end and the resulted triangular backflows should be avoided for skew bridge.
3.1.5 For plains and flood plains, bridges and culverts shall be reasonably arranged according to flood diversion facilities.
3.1.6 The centerline of bridge site on the operational rivers should he orthogonal to the shipping line. Rechanneled water courses shall be taken into account as to effects on shipping span.
3.1.7 The bridge structure should be designed to be orthogonal. When the skew is unavoidable, the angle between the bridge axis and the support line should be no smaller than 60°. The abutment margin of the skew bridge abutment shall be perpendicular to the center line, otherwise special transition measures shall be taken to connect with the subgrade if the abutment margin can not be perpendicular to the center line.
3.1.8 The ride comfort requirements, construction process requirements of the transition section between subgrade and bridge (culvert), technical economy and other factors shall be taken into consideration during the determination of embankment length between adjacent bridges and culverts.
3.1.9 The design of diversion and control structures shall meet the following requirements:
1 The top surface of diversion and control structures that are not immersed shall be higher than the water level of designed flood frequency by at least 0.25 m (consideration shall be also given to the slope of water surface). Where necessary, study into the effects of back water level, height of hitting waves, local flow uprush, partial skew flow uprush, cant of cove, river bed sedimentation etc.
2 The top surface of diversion and control structures that are immersed should be higher than normal water level.
3 The water face of diversion and control structures that are not immersed shall be equipped with full-height protection. And the immersed diversion and control structures shall be protected at both sides and top surface. The protection criteria for various diversion and control structures may he determined by the impacts of water streams, waves, drift ice, drift wood, drifters, etc. Scour shall be considered when it comes to the design of slope toe.
3.1.10 When building the bridge on the second line, many factors such as national defense requirements, hydrographic and geological conditions, working conditions of bridge on the existing track, status of infrastructure, navigation requirements, interferences in construction and traffic shall be taken into account to decide the layout of the bridge. If the bridge on the second line and bridge on the existing line are located in the area of water current interference, the centerlines of pier and abutment should correspond to each other along flow.
3.1.11 For bridges and culverts to be renovated, the original alignment and location shall remain unchanged if they are still acceptable in terms of plan and profile.
3.2 Aperture of Bridge and Culvert
3.2.1 The aperture of bridge and culvert shall be designed to ensure safe access for design (check) frequency floods. And the impacts of backwater and scour on upper and lower reaches shall be considered in the design to ensure the reliability of the embankment adjacent to the bridge and culvert.
3.2.2 The aperture design of bridges crossing rivers and artificial channels shall meet the following requirements:
1 The alteration of river bed shall be considered and the natural status of water currents should not be changed.
2 In case the river bed is likely to be scoured, the allowable coefficient of scour should not exceed the values specified in Table 3.2.2.
Table 3.2.2 Allowable Coefficient of Scour
Types of rivers Coefficient
of Scour Note Types of rivers Coefficient of scour Note
Mountainous areas Gorge areas ≤1.2 Without beach Area in front of mountains Stable river reaches ≤1.4 -
Open areas ≤1.4 With beach
Plain areas ≤1.4 - Rechanneled river reaches Determined by local experience -
Note: when the average depth of wide-shallow rivers is 1.0 m or below, the allowable coefficient of scour shall be determined by local experience.
3 After calculating the aperture of the bridge in the plain areas by coefficient of scour, the effects of back water in front of the bridge on the upper reaches shall be avoided or minimized.
4 The bridge aperture on the artificial channel should not be narrowed. Instead, the number of piers in the water channel shall be reduced.
5 The aperture of bridge in debris flow areas shall be designed reasonably based on the basic river width.
6 With regard to the aperture of bridge that may be influenced by the reservoir, its design shall respect not only the natural conditions of rivers, but also the changes of river conditions caused by the reservoir. For the bridge aperture adjacent to the downstream of the reservoir, the impact of dam break shall be considered if the bridge is under design flood frequency and the safety of dam is insufficient.
3.2.3 General scour and partial scour near the pier and abutment shall be calculated and the impacts of the alteration of river bed natural down-cutting of water courses caused by flood shall be considered. While designing the bridge at the downstream of the dam, the impacts of the partial scour at the dam bottom and clear-water scour shall also be considered.
3.2.4 The long and medium bridges of new railway shall not be with the method of river bed paving under the bridge.
3.2.5 For the aperture of bridge which is unnavigable and no rafting, the clearance height under bridge shall be in accordance with those specified in Table 3.2.5. The navigable aperture serving rafts, clearance under bridge and designed navigable water level shall be determined after communication with shipping and rafting authorities. Concerning rivers with drift ice or drift wood, the design of the clearance under bridge should be determined by the actual survey data.
Table 3.2.5 Clearance Height under Bridge
Part of bridge Minimum clearance height above the elevation (after design flood frequency water level plus Δh)(m) Minimum clearance height above the elevation (after check flood frequency water level plus Δh)(m)
Girder
bottom Without major drifters during flood season 0.50 0.25
With major drifters during flood season 1.50 1.00
With debris flow 1.00 -
Top of bearing pad stone 0.25 -
Arch fib and springing of arch ring 0.25 -
Notes: 1 The "design (or cheek) flood frequency water level" in the table refers to the design (or check) flood frequency water level in Table 1.0.9 in Article 1.0.9. Δh indicates the height reapectively impacted by back water, wave height, river bead superelevation, river bed sedimentation, partial flow uprush, etc., according to the actual situations of rivers.
2 For rivers without major drifters in flood seasons, the arch springing of filled spandrel hingeless arch bridges are allowed to be immersed by the water level of designed flood frequency plus Δh. However, the water level shall not exceed half of arch rise. And the clearance height from the top of arch shall he at least 1.0 m.
3 If a great debris flow attacks or major drifters pass through under the steel girder during flood period, the clearance height shall be larger than the values listed in the above table based on the practical situation.
3.2.6 For the overpass bridge and culvert which railway and road cross over each other, the clearance under bridge shall be in line with relevant technical standards. When the autos run through leaving the clearance under bridge less than 5 re, the height limited protective frame shall be set.
3.2.7 The culvert should be designed as a unsubmerged type. In the unsubmerged culvert, the clearance height from the inner top of culvert to the highest water flow level shall be determined according to those specified in Table 3.2.7.
Table 3.2.7 Clearance Height from the Inner Top of Culvert to the Highest Water Flow Level of Unsubmerged Culvert
Clearance height of culvert structure H (m) Circular culvert Arch culvert Rectangular culvert
≤3 ≥H/4 ≥H/4 ≥H/6
>3 ≥0.75 m ≥0.75 m ≥0.50 m
3.3 Structure of Bridge and Culvert
3.3.1 The aperture and style of bridges and culverts in the same section shall not be diversified. Except for the bridge and culvert for navigation and overpass or other special demands, one bridge should have equal spans and the same bridge superstructure.
3.3.2 For brook with debris flow or water flow containing a lot of sandstones, everfrost areas with ice cones and ice mound as well as areas that may be flooded, bridges should be built. Discharge tunnel may be adopted for curved river valley as long as the valley's hydrogeological conditions permit. Circular culverts on a large-scale irrigation channel should not be adopted.
3.3.3 The building materials for the bridge and culvert structure shall be selected in accordance with manufacturing level and supply capability of materials. Plain concrete, reinforced concrete, prestressed concrete or steel may be taken as options.
3.3.4 Good drainage, good ventilation and required maintenance space shall be guaranteed for bridge and culvert structure. The waterproofing and drainage facilities of the bridge shall be determined according to the form and layout of the track, and shall meet the following requirements:
1 Effective waterproofing measures shall be taken on girder ends or girder joints.
2 A reasonable drainage slope and surface shape of girder and abutment shall make benefit to drainage.
3.3.5 The arrangement of the bridge fixed bearing seat in the longitudinal direction of the bridge shall comply with the following requirements:
1 Position it at the lower end in the ease of gradient.
2 Position it at the end closer to the station if the fixed bearing is adjacent to the station.
3 Position it at the front end of direction of the heavy train on the section flat track.
4 The fixed bearings for adjacent beams should not be installed on the same pier.
5 If the above conditions conflict with each other, the requirement for the gradient shall be realized first.
3.3.6 The lateral displacement restraint conditions of the bearings on the same side of the track in the same bridge should be the same.
3.3.7 When the width difference between the inner and outer sides of the same girder joints is large, it is advisable to adjust the cantilever end in the girder end of bridge deck.
3.4 Bridge Approach and Tracks on the Bridge
3.4.1 The track shoulder elevation of bridge approaches of very long, long and medium bridges shall be at least 0.5 m higher than the designed flood frequency water level (consideration shall be also given to the water surface gradient) plus impact from back water level, height of hitting waves, local flow uprush, partial skew flow uprush, superelevation of river bend and river bed sedimentation etc. The shoulder elevation of short bridge and culvert shall be at least 0.5 m higher than the designed flood frequency water level plus back water level.
3.4.2 The connection between abutment and subgrade shall conform to the following requirements:
1 The upper part of abutment tail shall be extended into the shoulder of subgrade by at least 0.75 m.
2 The distance between the surface of conic pitching and the after edge of top surface of bearing pad stone shall be at least 0.30 m.
3 The toe of cone along the abutment should not stretch out of the front edge of abutment body if the toe of cone is under soaking.
4 The grade of the cone along the direction of the track shall not be steeper than that specified in Table 3.4.2.
Foreword I
1 General Provisions
2 Terms and Symbols
2.1 Terms
2.2 Symbols
3 Layout of Bridge and Culvert
3.1 General Requirements
3.2 Aperture of Bridge and Culvert
3.3 Structure of Bridge and Culvert
3.4 Bridge Approach and Tracks on the Bridge
3.5 Deck Layout and Ancillary Facilities
3.6 Maintenance and Repair Facilities
3.7 Structural Design and Safety Protection of Crossing Railway Bridge
3.8 Bridge Structure of Elevated Station
3.9 System Interface Design
4 Design Loads
4.1 Load Classification and Combination
4.2 Dead Loads
4.3 Live Loads
4.4 Other Loads
4.5 Service Passageway Loads and Railing Loads
4.6 Construction Loads
5 Design of Bridge and Culvert
5.1 General Requirements
5.2 Beam Bridge
5.3 Arch Bridge
5.4 Pier and Abutment
5.5 Culvert
5.6 Jacking Bridge and Culvert
Appendix A Active Earth Pressure Calculation
Appendix B Static Earth Pressure Calculation
Appendix C Distribution Diagram of Reference Wind Pressure in China
Appendix D Illustration of Calculating Temperature of Rectangular Section
Appendix E.1 Average Air Temperature (℃) in January in China
Appendix E.2 Average Air Temperature (℃) in July in China
Words Used for Different Degrees of Strictness
