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This standard is redrafted based on "Design Guideline for Boiler Steel Framework" (JB/T 6736-1993) and "Seismic Design Standard for Boiler Structure" (JB 5339-1991).
Compared with JB/T 6736-1993 and JB 5339-1991, the main changes in this standard are as follows:
- This standard is based on "Design Guideline for Boiler Steel Framework" (JB/T 6736-1993) and "Seismic Design Standard for Boiler Structure" (JB 5339-1991); current relevant national standards are referred and the particularity of boiler steel structure is considered;
- The calculation formula and damping ratio for basic natural vibration period of boiler steel structure are defined;
- The former manual static analysis is replaced by plane and spatial static analysis due to the fact that the static analysis of boiler steel structure is basically carried out with computer currently;
- Design contents of stop log are added;
- Calculation formula for the bottom plate of hinged column is revised according to the ultimate limit state of bearing capacity;
- Function and arrangement principle of brace system are defined;
- Welded-bolted connection contents are added;
- The section for typical connection calculation of high strength bolt is added;
- Calculation method for connecting piece at the connection node is added;
- Seismic structural measures and relevant requirements of boiler steel structure, design of stiffening bar, boiler platform and stair and anti-rust and anti-corrosion treatment of boiler steel structure are added.
This standard is proposed by and under the jurisdiction of National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).
Drafting organizations of this standard: Subcommittee on Boiler Steel Structure of China Steel Construction Association, Shanghai power equipment Research Insitute.
Chief drafting staff of this standard: Li Dasehng, Jia Tianxin, Sun Hongpeng, Ma Weiyan, Wang Guohong, Wang Yi, Ye Guoping, Dai Qingsheng, Li Liren, Meng Xianguo and Cheng Zhenlin.
This standard is issued for the first time.
Specification for Design of Boiler Steel Structures
鍋爐鋼結(jié)構(gòu)設(shè)計(jì)規(guī)范
1 Scope
This standard specifies the design principles and methods of bottom-supported and top-supported boiler steel structures.
This standard is applicable to the design of bottom-supported and top-supported boiler steel structures.
2 Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments to (excluding amending errors in the text), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of the normative document is applicable. For undated references, the latest edition of the normative document applies.
GB/T 700 Carbon Structural Steels (GB/T 700-2006, ISO 630: 1995, Structural Steels - Plates, Wide Flats, Bars, Sections and Profiles, NEQ)
GB/T 1228 High Strength Bolts with Large Hexagon Head for Steel Structures [GB/T 1228-2006, ISO 7412: 1984, Hexagon Bolts for High Structural Bolting with Large Width across Flats(Short Thread Length) - Product Grade C - Property Classes 8.8 and 10.9, NEQ]
GB/T 1229 High Strength Large Hexagon Nuts for Steel Structures (GB/T 1229-2006, ISO 4775: 1984, Hexagon Nuts for High Strength Structural Bolting with Large Width across Flats - Product Grade B - Property Classes 8 and 10, NEQ)
GB/T 1230 High Strength Plain Washers for Steel Structures (GB/T 1230-2006, ISO 7416: 1984, Plain Washers, Chamfered, Hardened and Tempered for High Strength Structural Bolting, NEQ)
GB/T 1231 Specifications of High Strength Bolts with Large Hexagon Head, Large Hexagon Nuts, Plain Washers for Steel Structures
GB/T 1591 High Strength Low Alloy Structural Steels
GB/T 3632 Sets of Torshear Type High Strength Bolt Hexagon Nut and Plain Washer for Steel Structures
GB/T 5117 Carbon Steel Covered Electrodes
GB/T 5118 Low Alloy Steel Covered Electrodes
GB/T 5313 Steel Plate with Through-thickness Characteristics
GB 50009 Load Code for the Design of Building Structures
GB 50011 Code for Seismic Design of Buildings
GB 50017-2003 Code for Design of Steel Structures
GB 50205 Code for Acceptance of Construction Quality of Steel Structures
3 Symbols and Abbreviations
3.1 Action and effect
F - the concentrated load;
FEk and FEvk - the characteristic values of the total horizontal and vertical earthquake actions of the structure;
Geq - the representative value of equivalent total gravity load of the structure when calculating the earthquake action;
M - the bending moment;
N - the axial force;
P - the pretension of high strength bolt; the recoil force of safety valve;
Q - the prying force;
S - the design value of action effect combination;
SE - the earthquake action effect;
Sk - the effect of characteristic values of load and effect;
R - the counter force of support;
T - the applied tension;
V - the shear force;
ωk - the characteristic value of wind load;
ω0 - the basic wind pressure;
σ - the normal stress;
σc - the local compression stress;
τ - the shear stress;
υ - the deflection.
3.2 Calculation indexes
E - the elastic modulus of steel;
Nbt, Nbv and Nbc - the design values for the tensile, shear and bearing capacity of a bolt;
R - the design value for the resistance of structural member;
f - the design values for the tensile, compressive and bending resistance of steel;
fv - the design value for the shear strength of steel;
fce - the design value for the bearing strength of steel end face;
fy - the yield strength (or yield point) of steel;
fbt, fbv and fbc - the design values for the tensile, shear and bearing strength of bolt;
fwt, fwv and fwc - the design values for the tensile, shear and compressive strength of butt weld;
fwf - the design values for the tensile, shear and compressive strength of fillet weld;
fc - the design value for the axial compressive strength of concrete.
3.3 Geometrical parameters
A - the gross sectional area;
An - the net sectional area;
I - the inertia moment of gross section;
In - the inertia moment of net section;
S - the area moment of gross section;
W - the gross section modulus;
Wn - the net section modulus;
d - the diameter;
d0 - the hole diameter;
h - the height;
he - the calculated thickness of fillet weld;
hf - the weld leg dimension of fillet weld;
i - the turning radius of section;
l - the length or span;
t - the thickness;
λ - the slenderness ratio.
3.4 Calculation coefficients and others
T - the natural vibration period of the structure;
nf - the number of force-transmitting friction surfaces of high strength bolt;
α - the horizontal seismic influence coefficient; the linear expansion coefficient; the moment coefficient of four-side-supported bottom plate;
β - the moment coefficient of three-side-supported or two-side-supported bottom plate;
βb - the coefficient of equivalent critical bending moment for the overall stability of beam;
βf - the amplification coefficient for the design strength value of the front fillet weld;
βgz - the gust coefficient at the height of z;
βm and βt - the equivalent bending moment coefficient for the stability of bending member;
βz - the gustiness factor at the height of z;
β1 - the amplification coefficient for the design strength value of reduced stress;
η - the adjustment coefficient;
μ - the anti-sliding coefficient for the friction surface of high strength bolt; the calculated length coefficient of column;
μs - the wind load shape coefficient;
μz - the height variation coefficient of wind pressure;
ξ - the pulsation enhancement coefficient of wind load; the parameter used to calculate the overall stability of beam;
v - the pulsation influence coefficient of wind load;
φz - the structural vibration mode coefficient;
ζ - the Structural damping ratio;
φ - the stability coefficient of axial compressive member;
φb and φ′b - the overall stability coefficient of beam;
γRE - the seismic adjustment coefficient of bearing capacity;
ψ - the combination value coefficient.
4 General Requirements
4.1 This standard is formulated in order to implement the current national standard in the boiler steel structure design and achieve advanced technology, economic rationality, safety and usability and guaranteed quality by considering the particularity of boiler steel structure
4.2 Boiler steel structure shall support all components of boiler body and maintain the relative position between them, and shall also bear wind load, snow load, earthquake action and other load provided by other design organization through the agreement of boiler design organization acted on the boiler steel structure. Except the particular requirements, boiler steel structure shall not directly bear the dynamic load.
4.3 The boiler steel structure shall adopt limit state design method based on probability theory, adopt the design expression of partial coefficient for calculation and adopt limit state of bearing capacity and limit state of normal use for design.
4.4 If the boiler steel structure is designed based on the limit state of bearing capacity, the fundamental combination of load (action) effect shall be considered; where necessary, the occasional combination of load (action) effect shall be considered. If the boiler steel structure is designed based on the limit state of normal use, the characteristic combination of load (action) effect shall be considered.
4.5 The boiler steel structure in area with seismic fortification intensity of Degree 6 or above shall be subjected to seismic design. This standard is applicable to the design of boiler steel structure with seismic fortification intensity of Degrees 6~9. If the intensity is greater than Degree 9, it shall be in accordance with the relevant requirements.
4.6 Checking calculation of wind resistance shall be carried out to the boiler steel structure arranged in the open air or closed tightly.
4.7 The member shall avoid high temperature (above 150℃) action as possible, as for the member subjected to high temperature action for long term, suitable steel shall be selected and meanwhile necessary thermal insulation or cooling measures shall be taken.
4.8 During the design of boiler steel structure set at cold area, measures shall be taken to improve the brittle fracture resistance of steel structure.
4.9 No matter what connection type is adopted for the node of boiler steel structure, where the node is regarded as rigid connection, it shall meet the assumption that the intersection angle of member at node point is unchanged in load-bearing process, at the same time, the connection shall be provided with sufficient strength to bear all the most unfavorable internal force transmitted from the intersectional member end; where the node is regarded as hinged connection, the connection shall be provided with sufficient rotation capacity but it shall be able to transmit the horizontal shear force and axial force effectively.
4.10 Unless otherwise specified, the importance coefficient γ0 of boiler steel structure shall be 1.0.
4.11 The natural environmental conditions required for design of boiler steel structure include:
a) Basic wind pressure;
b) Ground roughness category;
c) Reference snow pressure;
d) Seismic fortification intensity (design basic seismic acceleration);
e) Design earthquake group;
f) Site category;
g) Working temperature.
4.12 The design of boiler steel structure shall be in accordance with the supply contract and technical agreement signed with the user and shall cooperate closely and intercoordinate with other design organization.
Foreword I
1 Scope
2 Normative References
3 Symbols and Abbreviations
4 General Requirements
5 Requirements for Material, Design Index and Structure (Member) Deformation
6 Arrangement of Boiler Steel Structure
7 Action and Its Effect Combination
8 Static Analysis
9 Beam Design
10 Column Design
11 Design of Brace System
12 Connection Design
13 Seismic Structural Measures and Relevant Requirements of Boiler Steel Structure
14 Stiffening Bar Design
15 Design of Boiler Platform and Stair
16 Anti-rust and Anti-corrosion Treatment of Boiler Steel Structure
