1 General Provisions
1.0.1 This code is formulated with a view to make the design of highway bridges and culverts meet the requirements of state-of-art technology, safety and reliability, durability and applicability as well as economic feasibility.
1.0.2 This Code is applicable to the design of the general reinforced concrete and prestressed concrete structural members for highway bridges and culverts, and it is not applicable to the design of light aggregate concrete structural members or other special concrete structural members.
1.0.3 This Code is formulated according to the design philosophy specified in the national standard "Unified standard of reliability design of highway engineering structures" (GB/T 50283-1999). The basic terms and symbols are adopted according to the requirements of the national standard “Basic terms and general symbols of structure deign" (GBJ 132-90) and "Terms of Road Construction" (GBJ 124-88).
1.0.4 This Code adopts probabilistic theory-based limit design method and designs according to the designed expression of partial safety factor.
The design reference period of this Code is 100 years.
1.0.5 The following two limit designs shall be carried out for the highway bridges and culverts:
1 Bearing capacity limit state: it corresponds to the state when the bridges and culverts and their members reach the maximum carrying capacity or deformation or deflection occurs indicating the aforesaid are not suitable for continuous bearing.
2 Regular service limit states: it corresponds to the certain state when the bridges and culverts and their members reach the limit of regular service or durability.
1.0.6 The following three design situations and their corresponding limit design shall be considered for the highway bridges and culverts:
1 Persistent situation: it refers to the situation that the finished bridges and culverts sustain their deadweight and car load etc. for a very long time. Bearing capacity limit state design and regular service limit state design shall be carried out for such bridges and culverts.
2 Transient situation: it refers to the situation when the bridges and culverts sustain temporary action (or load) in the construction process. Bearing capacity limit state design shall be carried out for such bridges and culverts, and regular service limit design can be carried out when necessary.
3 Accidental situation: it refers to the situation that a sporadic earthquake occurs when the bridges and culverts are under usage. Bearing capacity limit design is the only design required for such bridges and culverts.
1.0.7 According to the environmental conditions, the durability design shall be carried out for the highway bridges and culverts. The basic requirements of durability for the structural concrete shall meet the requirements of Table 1.0.7.
Table 1.0.7 Basic Requirements of the Durability for Structural Concrete
Environment classification Environmental condition Maximum water cement ratio Minimum cement content(kg/m3) Minimum concrete strength level Maximum chloride ion content (%) Maximum alkali content(kg/m3)
I Atmospheric environment in warm or cold regions and environment with no connection to corrosive water or soil 0.55 275 C25 0.30 3.0
II Atmospheric environment in chilly areas, ice-removal salt-used environment and littoral environment 0.50 300 C30 0.15 3.0
III Briny environment 0.45 300 C35 0.10 3.0
IV Environment influencing by corrosive substance 0.40 325 C35 0.10 3.0
Note: (1) If the maximum water cement ratio and minimum cement content of structural concrete in the briny environment are specified in more detail in relevant governing codes, these codes may be complied with;
(2) The chloride ion content in the Table refers to the percentage of chloride ion to cement content;
(3) With actual engineering experience, the minimum strength level of structural concrete under Class I environment can be a grade lower what specified in the Table;
(4) As for the prestressed concrete members, its maximum chloride ion content is 0.06%, minimum cement content is 350kg/m3, minimum concrete strength level is C40 or three grades higher than what specified in Class I environment or two grades higher than other types of environments;
(5) As for the outsized and large bridges, the maximum alkali content of concrete should be reduced to l.8kg/m3; when it is under Class III, Ⅳ or ice-removal salt-used and littoral environment, non-alkali aggregate should be adopted. The definitions for outsized bridges and large bridges are given in Table 5.1.2 of this Code.
1.0.8 As for the bridge bridges under Class III or Class IV environment, if the durability in required, their major tension reinforcement should be epoxy coating steel reinforcement; and special protective measures shall be adopted for the prestressed reinforcement, anchorage and connectors.
1.0.9 As for structural concrete in mobile water region and with freezing resistance requirements, its freezing resistance rating shall not be lower what specified in Table 1.0.9.
Table 1.0.9 Standard for Selection of Freezing Resistance Rating of Concrete in Mobile Water Regions
Bridge location Briny environment Freshwater environment
Severely frost areas (with the monthly mean temperature of the coldest month lower than -8℃) F350 F250
Frost areas (with the monthly mean temperature of the coldest month between -4℃~-8℃) F300 F200
Partial freezing areas (with the monthly mean temperature of the coldest month between 0℃~-4℃) F250 F150
Note: (1) The freezing test method for concrete shall meet the requirements of the current standard "Testing Methods of Concrete for Highway Engineering" (JTJ 053-94);
(2) The freezing resistance rating for pier and platform concrete shall be a grade higher than what specified in the Table.
The frost-resistant concrete shall be added with proper amount of air-entraining agent, the air content of the mixture shall meet the current code "Technical Specifications for Construction of Highway Bridges and Culverts" (JTJ 041-2000).
1.0.10 As for the structural concrete with impervious requirements, its impermeability rating shall meet the requirements of Table 1.0.10.
Table 1.0.10 Standard for the Selection of Impermeability Rating for Structural Concrete
Ratio of the maximum acting head to concrete wall thickness Impermeability rating Ratio of the maximum acting head to concrete wall thickness Impermeability rating
<5 W4 16-20 Wl0
5~10 W6 >20 W12
11 ~ 15 W8
Note: The impermeability test method of concrete shall meet the requirements of the current standard "Testing Methods of Concrete for Highway Engineering" (JTJ 053-94).
1.0.11The engineering and construction quality of bridge structure shall be supervised and controlled strictly in stages; the bridges shall be used according to the specified working conditions by the design, overloaded vehicles are prohibited to pass through; during the process of usage, periodic inspection and maintenance must be carried out.
1.0.12If the design is carried out according to this Code, the relevant action (or load) and their combination shall meet the requirements of "General Code for Design of Highway Bridges and Culverts" (JTG D6O-2004); the material and engineering quality shall meet the requirements of "Quality Inspection and Evaluation Standards for Highway Engineering" (JTJ 071-98) and "Technical Specifications for Construction of Highway Bridges and Culverts" (JTJ 041-2000); the structural aseismic design shall meet the requirements of "Specifications of Earthquake Resistant Design for Highway Engineering" (JTJ 004-89).
2 Terms and Symbols
2.1 Terms
2.1.1 Limit states
If the overall structure or part of the structure cannot meet certain designed functional requirements when they exceed specific conditions, then such specific condition can be defined as the limit state of this function.
2.1.2 Degree of reliability
It refers to the probability that the structure complete the intended functions within the stipulate time and under defined conditions.
2.1.3 Design reference period
It refers to the reference time parameters that are adopted for considering the relation between each basic variable and time under persistent design situation when analyzing the structural reliability.
2.1.4 Design situation
It refers to a group of physical conditions within certain period in the overall process from construction to usage; the structure shall not exceed any concerned limit state within such period.
2.1.5 Characteristic value of material strength
It refers to the basic representative value of the material strength adopted at designing the structure or member. This value may be determined according to strength probability distribution (tantile: 0.05) of the material that complies with the standard.
2.1.6 Design value of material strength
It refers to the value acquired from dividing the characteristic value of material strength by the partial safety factor of material strength.
2.1.7 Action
The concentrated force or distributed force exerted on the structure (for instance: dead load of the car and structure) and earthquakes/differential settlement/ temperature variation etc. that can cause deformation or restrained deformation to the structure go by the general name of action. The former is direct action, and can be called as load; while the latter is indirect effect (should not be called as load).
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3 Materials
3.1 Concrete
3.1.1The strength level of concrete shall be determined according to normal value of compressive strength of the cube specimen whose side length is 150mm. The normal value of compressive strength (in MPa) refers to the compressive strength which is determined according to the standard test method and whose factor of assurance is 95%, thereinto, the specimen is manufactured with a standard method and shall be cared for 28d.
Note: (1) The strength level of concrete is the normal value of compressive strength of 150mm×150mm×150mm cube and represented by C, for instance: C30 represents the concrete of level 30.
(2)The concrete strength level in this Code, the concrete grades in the "Design specification of highway reinforced concrete and prestressed concrete bridges and culverts" (JTJ 023-85) and the relation between the design index of each items may be adopted according to the requirements of Appendix A.
3.1.2The strength level of concrete for the load-bearing members of highway bridges and culverts shall be adopted according to the following requirements:
1 The strength level of concrete for reinforced concrete members shall not be lower than C20, if HRB400 and KL400 distributed steel are adopted, it shall not be lower than C25.
2 The strength level of concrete for prestressed concrete members shall not be lower than C40.
3.1.3 The normal value of compressive strength and normal value of tensile strength of the concrete axis shall be adopted according to Table 3.1.3.
Table 3.1.3 Normal Value of Concrete Strength (MPa)
1 General Provisions
2 Terms and Symbols
2.1 Terms
2.2 Symbols
3 Materials
3.1 Concrete
3.2 Steel reinforcement
4 General Requirements of Bridge Calculation
4.1 Plate Calculation
4.2 Beam Calculation
4.3 Arch Calculation
5 Calculation of Bearing Capacity Limit State under Persistent Situation
5.1 General Provisions
5.2 Bending Member
5.3 Compression Member
5.4 Tension member
5.5 Torsion member
5.6 Punching member
5.7 Partial compression member
6 Calculation of Serviceability Limit States in Permanent Situation
6.1 General provisions
6.2 Pre-stress loss of steel reinforcement
6.3 Anti-cracking recalculation
6.4 Recalculation of crack width
6.5 Recalculation of Deflection
7 Stress Calculation of Members in Permanent and Transient Situations
7.1 Stress calculation of pre-stressed concrete members in permanent situation
7.2 Stress calculation of member in transient situation
8 Provisions on member calculation
8.1 Combined type bending member
8.2 Pier cap-beam
8.3 Reamer
8.4 Rubber bearing
8.5 Pile foundation and cushion cap
8.6 Bridge retractor device
9 Specifications on Construction
9.1 General provisions
9.2 Slabs
9.3 Beam
9.4 Prestressed Concrete Superstructure
9.5 Arch Bridge
9.6 Column, Butment and Pile Foundation Bearing Platform
9.7 Bearing
9.8 Culvert, Hoisting Ring and Hinge
Annex A Concrete Strength Grades in This Code and Concrete Grade in the Original "Code for Design of Reinforced Concrete and Prestressed Concrete Highway Bridges and Culverts" (JTJ 023-85) as well as Relations between Their Design Indexes
Annex B Calculation Formulae for Temperature Action Effects
Annex C Compression Resistant Bearing Capacity Calculation of Normal Sections of Round-section Reinforced Concrete Eccentric Compression Members
Annex D Simplified Calculation for Post-anti-friction Prestress Loss of Prestressed Curved Reinforcements caused by Anchorage Deformation, Reinforcement Retraction and Joint Compression
Annex E Simplified Calculation for Elastic Compression Loss of Post-stressed Concrete Members
Annex F Concrete Shrinkage Strain and Creep Coefficient Calculation and Ratio of the Medium Value to the Ultimate Value of Steel Relaxation Loss
Annex G Compression Area Height Calculation of Class B Prestressed Concrete Bending Members Allowing Cracks
