1 General
1.0.1 Following the principle to be safe, durable, applicable, environmental-friendly, economic and shapely, this Specification is laid down to regulate the design of highway steel bridge, improve the design capability and assure engineering quality.
1.0.2 This Specification is applicable to the design of the bridge with steel structure and the steel structure of bridge for all levels of highway.
1.0.3 For this Specification, design is carried out with the design expression of partial factor, using the probability theory-based ultimate design method.
1.0.4 Highway steel bridges shall have durability design--for extra-large, large and medium bridges, the major structure shall be designed as per a service life not less than 100 years; for small bridge on motorway, Class I highway and Class II highway, it should also be designed as per a service life not less than 100 years.
1.0.5 Highway steel bridges shall consider the design conditions and perform appropriate ultimate design, as specified in "General Specifications for Design of Highway Bridges and Culverts" (JTG D60-2015).
1.0.6 The design of highway steel bridge shall propose requirements for manufacture, transport, installation, maintenance and management, and select appropriate structure form, should adopt standardized and generalized structural units and members, and shall adopt such construction and connection that are easy for fabrication, erection, inspection and maintenance.
1.0.7 Highway steel bridge design shall meet the requirements of the current applicable national and professional standards, besides this Specification.
2 Terms and Symbols
2.1 Terms
2.1.1 Buckling
Stability failure of member bar or slab caused by a fairly large deformation from the original stress state which breaks out under the individual or joint action of axial pressure, bending moment and shear force.
2.1.2 Overall stability
The ability of the whole structure or member to resist lateral buckling or unstability under the action of external load.
2.1.3 Local stability failure
Buckling happened to the slab in steel structure under pressure, bending, shearing or complex stress, due to excessive width-to-thickness ratio.
2.1.4 Effective width
The part of width in which slab is assumed effective, for the calculation of section strength and stability.
2.1.5 Effective width factor
The ratio of the effective width to the actual width of slab.
2.1.6 Effective length
A length equal to the geometrical length of member between the effective confined points multiplied by a factor incorporating the deformation and loading at bar ends, which is use for calculating the slenderness ratio of member.
2.1.7 Effective length of weld
The weld length used for calculating the weld joint strength.
2.1.8 Slenderness ratio
The member ratio of the effective length to the radius of gyration.
2.1.9 Equivalent slenderness ratio
For calculating the overall stability of axial compression member, the resultant slenderness ratio as latticed member is converted to solid web member according to principle of equivalent critical force, or the slenderness ratio used for converting bending-torsional and torsion stability failure to bending stability failure.
2.1.10 Steel and concrete composite beam
A member in which steel beam is well integrated and, within the cross-section, able to bear loading jointly with concrete slab.
2.1.11 Compressed slab
Steel slab which bears compressive stress.
2.1.12 Stiffened plate
The parts with stiffening ribs, of a longitudinal stiffening rib-reinforced flange divided by web and diaphragm, or of a longitudinal/transverse stiffening rib-reinforced web divided by flange and diaphragm, which comprise parent plate and stiffening ribs (welded on the parent plate).
2.1.13 Sub-panel
The parts without stiffening rib, of stiffened plate divided by stiffening ribs.
2.2 Symbols
2.2.1 Symbols associated with material properties
fy - the yield strength of steel;
fd - the design value of tensile, compressive and bending strength of steel;
fvd - the shear strength design value of steel;
fcd - the design value of bearing strength at end face of steel;
fatd - the design value of tensile strength of anchor bolt;
fwfd - the design values for the tensile, shear and compressive strength of fillet weld;
fbtd, fbvd, fbcd - the design values for the tensile, shear and bearing strength of bolt;
frtd, frvd, frcd - the design values for the tensile, shear and bearing strength of rivet;
fwtd, fwvd, fwcd - the design values for the tensile, shear and compressive strength of butt weld;
E - the elastic modulus of steel;
Ec - the elastic modulus of concrete;
G - the shear modulus of steel.
2.2.2 Symbols associated with effect of action and resistance
Nd - the design value of axial force;
Ncr,y, Ncr,z - the Euler load for the overall stability of axial compression member;
Nv, Nt - the shear force and tensile force borne by a plain bolt or rivet;
Nbvd, Nbtd, Nbcd - the design values for the shear, tensile and compression-bearing capacity of a single bolt;
Nrvd, Nrtd, Nrcd - the design values for the shear, tensile and compression-bearing capacity of a single rivet;
P - the pretension force for a single high-strength bolt;
My, Mz - the design values for the bending moment of calculation section;
Mcr,y, Mcr,z - the overall bending-torsional elastic buckling moment of the member, considering restraint effect, under sole action of bending moment in the plane affected by My and Mz
σE,cr - the Euler stress for the elastic stability of axial compression member;
σmax, σmin - the maximum and minimum normal stress;
Δσk, Δτk - the standard values for the normal stress and shear stress of fatigue load;
ΔσC, ΔτC - the resistance of fatigue detail class;
τ - the shear stress;
τmax, τmin - the maximum and minimum shear stress.
2.2.3 Symbols associated with geometric parameters
a - length and spacing;
b - width;
d - diameter;
eN - eccentricity;
h - height;
hw - effective height of web plate;
l - length and span;
n - number of high-strength bolt(s);
t - thickness;
tw - thickness of web;
A - section area of member;
A0 - net sectional area;
Aeff - effective sectional area of compression flange, considering both shear lag and local stability effect;
Aeff,c - effective sectional area considering local stability effect;
Aeff,s - effective sectional area considering shear lag;
As - sectional area of steel beam;
Ac - sectional area of concrete deck slab;
It - torsional inertia moment of gross section;
Iω - sectorial inertia moment of gross section;
R - radius;
S - area moment;
Wy,eff, Wz,eff - section modulus of effective section in relation to y-axis and z-axis;
α, θi - included angle.
2.2.4 Calculation factors and other associated symbols
k - the elastic buckling coefficient of stiffened plate, and rigidity coefficient of connection;
kc - the conversion coefficient of bending moment;
n0 - the elastic modulus ratio of steel to concrete;
v - the Poisson's ratio;
χ - the overall stability reduction factor of axial compression member;
χLT,y, χLT,z - the member's overall stability reduction factor of bending-torsional stability failure mode, under sole action of bending moment in the plane affected by My and Mz;
λ - the slenderness ratio of axial compression member;
λx, λy - the slenderness ratio of member in relation to x-axis and y-axis;
- the relative slenderness ratio;
, - the relative slenderness ratio of axial compression overall stability;
, - the relative slenderness ratio of bending-torsional stability;
- the relative width-to-thickness ratio of compression plate;
βm,y, βm,z - the equivalent bending moment coefficient in relation to My and Mz;
φbx - the stability coefficient of bending member in the plane affected by bending moment;
γ0 - the structure importance coefficient;
μ - the impact factor, and anti-sliding coefficient of friction surface;
η - the bidirectional bending correlation coefficient.
3 Materials and Design Indexes
3.1 Materials
3.1.1 Materials shall be appropriately selected according to the structure type, stress state, connection method and in-situ environment conditions.
3.1.2 Q235, Q345, Q390 and Q420 steels should be selected and their quality shall comply with the current "Carbon Structural Steels" (GB/T 700) and "High Strength Low Alloy Structural Steels" (GB/T 1591), The rimmed steel in the said Q235 should not be used for welded structures which require for fatigue checking or those with no such requirement but with a working temperature lower than -20℃; nor non-welded structures with fatigue checking requirement and a working temperature lower than or equal to -20℃.
3.1.3 The impact toughness of the steel designations associated shall meet the following requirements:
1 For welded members requiring fatigue checking, when the bridge working temperature, t, ranges as 0℃≥t>-20℃, the impact toughness shall meet those specified for Quality Grade C in Table 3.1.3 for Q235 and Q345 and meet those specified for Quality Grade D for Q390 and Q420; when the bridge working temperature, t, ranges as t≤-20℃, that shall meet those specified for Quality Grade D for Q235 and Q345 and meet those specified for Quality Grade E for Q390 and Q420.
2 For non-welded members requiring fatigue checking, when the bridge working temperature, t, ranges as t≤-20℃, the impact toughness shall meet those specified for Quality Grade C in Table 3.1.3 for Q235 and Q345 and meet those specified for Quality Grade D for Q390 and Q420.
Table 3.1.3 Impact Toughness of Steel
Steel designation Q235 Q345 Q390 Q420
Quality grade C D C D D E D E
Test temperature (℃) 0 -20 0 -20 -20 -40 -20 -40
Impact toughness (J) 27 27 34 34 34 27 34 27
3.1.4 When Z-direction steel is used in welded structure, its quality shall comply with the current "Steel Plate with Through-thickness Characteristics" (GB/T 5313).
3.1.5 For the cast steel used in steel castings, its quality shall comply with the current "Carbon Steel Castings for General Engineering Purpose" (GB/T 11352).
3.1.6 Pins, hinges, shafts, stay cable anchorages and the like should adopt forged or rolled quality carbon structural steels of which the quality shall comply with the current "Quality Carbon Structural Steels” (GB/T 699).
3.1.7 The specifications of high-strength bolts, nuts and washers shall comply with the current national standards "High Strength Bolts with Large Hexagon Head for Steel Structures" (GB/T 1228), "High Strength Large Hexagon Nuts for Steel Structures" (GB/T 1229), "High strength Plain Washers for Steel Structures" (GB/T 1230), "Specifications of High Strength Bolts with Large Hexagon Head, Large Hexagon Nuts, Plain Washers for Steel Structures" (GB/T 1231) and "Sets of Torshear Type High Strength Bolt Hexagon Nut and Plain Washer for Steel Structures" (GB/T 3632).
3.1.8 Plain bolts shall comply with the current national standards "Hexagon Head Bolts - Product Grade C" (GB/T 5780) or "Hexagon Head Bolts" (GB/T 5782).
3.1.9 Rivets shall comply with the current "Hot-rolled Round Carbon Steel Bars and Rods for Standard Parts" (GB 715).
3.1.10 The materials for anchor bolts may adopt Q235 or Q345 steel of which the quality shall comply with the current "Carbon Structural Steels" (GB/T 700) or "High Strength Low Alloy Structural Steels" (GB/T 1591).
3.1.11 The materials for cheese head stud connection shall comply with the current national standard "Cheese Head Studs for Arc Stud Welding" (GB/T 10433).
3.1.12 Welding materials shall be suitable for the base steel and shall meet the following requirements:
1 The electrodes adopted for manual welding shall comply with the current "Carbon Steel Covered Electrodes" (GB/T 5117) or "Low Alloy Steel Covered Electrodes" (GB/T 5118).Members requiring fatigue checking should adopt low hydrogen basic electrodes.
2 The welding wires and fluxes used for automatic and semi-automatic welding shall comply with the current "Steel Wires for Melt Welding" (GB/T 14957), "Welding Electrodes and Rods for Gas Shielding Arc Welding of Carbon and Low Alloy Steel " (GB/T 8110), "Carbon Steel Flux Cored Electrodes for Arc Welding" (GB/T 10045), "Low Alloy Steel Flux Cored Electrodes for Arc Welding " (GB/T 17493), "Carbon Steel Electrodes and Fluxes for Submerged Arc Welding" (GB/T 5293) or "Low-alloy Steel Electrodes and Fluxes for Submerged Arc Welding" (GB/T 12470).
3.1.13 For the high-strength steel wires, strands and ropes used for stay cable, main cable and lifting cable, their technical performance shall meet the following requirements:
1 High-strength steel wires shall comply with the current "Hot-dip Galvanized Steel Wires for Bridge Cables" (GB/T 17101) or "Technical Conditions for Hot-extruding PE Protection High Strength Wire Cable of Cable-stayed Bridge” (GB/T 18365).
2 Steel strands shall comply with the current "Steel Strand for Prestressed Concrete" (GB/T 5224) or "High Strength Low Relaxation Hot-dip Galvanized Steel Strand for Prestress" (YB/T 152).
3 Steel wire ropes shall comply with the current "Steel Wire Ropes for Important Purposes" (GB 8918), "Steel Wire Ropes for General Purpose" (GB/T 20118) or “Large Diameter Steel Wire Ropes" (GB/T 20067).
3.1.14 The materials for hot cast anchor head body shall select low-melting-point zinc-copper alloys. The materials for cold cast anchor head body may be composed of epoxy resin, iron sand, mineral aggregate and curing agent of which the proportioning shall be determined upon test.
3.1.15 Structural steels for bridge members such as anchorage, connector, expansion device, damper and saddle shall comply with the current national and industrial product standards.
3.2 Design Indexes
3.2.1 The design strength of steel shall be valued by the steel thickness according to Table 3.2.1.
Foreword i
1 General
2 Terms and Symbols
2.1 Terms
2.2 Symbols
3 Materials and Design Indexes
3.1 Materials
3.2 Design Indexes
4 Structural Analysis
4.1 Structural Analysis Model
4.2 Structural Strength, Stability and Deformation Calculation
5 Member Design
5.1 General
5.2 Axial Load-bearing Member
5.3 Flexural Member
5.4 Tension-flexural and Compression-flexural Members
5.5 Anti-fatigue Design
6 Connection Structures and Calculation
6.1 General
6.2 Welded Connection
6.3 Bolted/Riveted Connection
7 Steel Plate Beam
7.1 General
7.2 Flange
7.3 Web
7.4 Longitudinal and Transverse Bracing System
8 Steel Box Beam
8.1 General
8.2 Orthotropic Steel Bridge Deck
8.3 Flange Plate
8.4 Web
8.5 Diaphragm Plate
9 Steel Trussed Beam
9.1 General
9.2 Bar
9.3 Gusset Plate
10 Steel Pipe Structure
10.1 General
10.2 Structure Requirements
10.3 Calculation Regulation
11 Steel and Concrete Composite Beam
11.1 General
11.2 Calculation of Ultimate State Bearing Capacity
11.3 Calculation of Normal Service Condition
11.4 Design of Connections
11.5 Structure
12 Steel Tower
12.1 General
12.2 Structure Requirements
13 Cable System
13.1 General
13.2 Structure Design
14 Pavement of Steel Deck
15 Protection and Maintenance Design
16 Support and Expansion Device
16.1 Support
16.2 Expansion Device
Appendix A Overall Stability Reduction Factor of Axial Compression Members
Appendix B Elastic Buckling Coefficient of Stiffened Compression Plate
Appendix C Fatigue Details
Appendix D Calculation Method of Damage Equivalent Coefficient
Appendix E Calculation of Tear Strength, Shear Stress and Normal Stress of Gusset Plate
Appendix F Calculation of Effective Width of Composite Beam Flange
Explanation of Wording in This Specification
