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GB/T 22395-2008 English PDF (GBT22395-2008)

GB/T 22395-2008 English PDF (GBT22395-2008)

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GB/T 22395-2008: Specification for design of boiler steel structures

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.
GB/T 22395-2008
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 27.060.30
J 98
Specification for Design of Boiler Steel Structures
ISSUED ON: SEPTEMBER26, 2008
IMPLEMENTED ON: MARCH 1, 2009
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Symbols and Abbreviations ... 6
4 General Requirements ... 9
5 Requirements for Material, Design Index and Structure (Member) Deformation . 11 6 Arrangement of Boiler Steel Structure ... 17
7 Action and Its Effect Combination ... 20
8 Static Analysis ... 36
9 Beam Design ... 39
10 Column Design ... 64
11 Design of Brace System ... 100
12 Connection Design ... 108
13 Seismic Structural Measures and Relevant Requirements of Boiler Steel Structure ... 132
14 Stiffening Bar Design ... 134
15 Design of Boiler Platform and Stair ... 139
16 Anti-rust and Anti-corrosion Treatment of Boiler Steel Structure ... 142 Specification for Design of Boiler Steel Structures
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 ??z - the height variation coefficient of wind pressure;
?? - 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;
??z - the structural vibration mode coefficient;
?? - the Structural damping ratio;
?? - the stability coefficient of axial compressive member;
??b and ???€?b - the overall stability coefficient of beam;
??RE - the seismic adjustment coefficient of bearing capacity;
?? - 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 ??0 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.
6.1.7 Combination type boiler steel structure has certain connection with boiler plant structure, for example: the boiler top beam gird is directly placed on the boiler plant structure, or the boiler steel structure has several connections with boiler plant structure, when one structure bears the load, it will affect the other structure. Combination type boiler steel structure should not be adopted generally.
6.2 Arrangement principle for boiler steel structure
6.2.1 Economic and reasonable structural system with good load carrying performance shall be selected for the boiler steel structure according to the features and external conditions of boiler. Plane and facade arrangement shall be regular and symmetrical and provided with good integrity to avoid structural stiffness mutation as possible.
6.2.2 In order to ensure the space working of structure, improve the integral stiffness of structure, bear and transmit horizontal force, avoid the lateral instability of compression rod and ensure the stability during structure installation, reliable brace system shall be arranged with different conditions of structure.
6.2.3 The arrangement of boiler steel structure shall consider the following items: a) Space and channel required for the support, hanging, installation, operation and maintenance of boiler body and accessory equipment.
b) Where there are seismic and wind resistance requirements, truss-type boiler steel structure should be selected.
c) The structure shall consider economic requirements:
1) The boiler steel structure and its components shall have simple structure and be convenient for manufacture;
2) Necessary member arrangement: boiler steel structure shall be arranged with member necessary for keeping its strength, stiffness and stability;
3) Direct transmission of load: the member shall transmit force explicitly to transmit the load to the foundation through beam, column and bracing in the shortest way; 4) The arrangement of column and beam shall ensure the minimum quantity of column; the length of beam should not be overlong; the arrangement of column and beam shall be analyzed and compared to adopt the most economical scheme; 5) Make the member be multi-use as possible and make full use of the characteristics of the member to make it bear multiple actions.
d) Easy of transportation and installation: the member shall avoid overweight and over-limit transportation and be ease of installation and emplacement.
7.2.7 Wind load distribution:
a) The boiler closed tightly or the boiler arranged outdoor without guiding device: distribute the wind load to the load-bearing node of boiler steel structure according to the wind area borne by each node of boiler steel structure based on the characteristic value of wind load of different height.
b) The boiler arranged outdoor with guiding device: calculate the wind load borne by each guiding device according to characteristic value of wind load of different height and the wind area of furnace restricted by the guiding device, and act it on the corresponding position of boiler steel structure. In this case, the wind load borne by each node of boiler steel structure shall be calculated by adopting appropriate wind area according to relevant requirements.
7.3 Earthquake action
7.3.1 Boiler steel structure after seismic fortification: under the effect of local frequent earthquakes, the buildings are generally free from any damage or can be in service continually without any repair; under the effect of the earthquakes at the local seismic fortification intensity, the buildings are possible to be damaged but still can be in service continually after general repair or without any repair; under the impact of the rare earthquake stronger than the local seismic fortification intensity estimation, the buildings are not collapsed or occurs life-threatening serious damage.
7.3.2 The seismic fortification intensity must be determined according to the document (drawing) examined, approved and issued by the authority as prescribed by the nation; generally, the basic seismic intensity in China's zonation map of ground motion parameter may be adopted.
7.3.3 For boiler steel structure with seismic fortification intensity of Degree 6, built in Category IV site and belongs to Category B building, boiler steel structure with Degree 7 or above, seismic checking of section under the action of frequent earthquakes shall be carried out. For boiler steel structure with irregular structural layout and visible weak layer, with height greater than 150m, or built in Degree 9 area and belongs to Category B buildings, elastic-plastic deformation under the action of rare earthquakes shall be carried out.
Where the seismic fortification intensity is Degree 6, besides the boiler steel structure built in Category IV site and belongs to Category B buildings, earthquake action calculation and seismic checking of section may not be carried out.
7.3.4 Power plant boiler steel structure with unit capacity of 300MW or above or planning capacity of 800MW or above belongs to Category B buildings and its earthquake action shall meet the requirements of local seismic fortification intensity. Generally, its seismic measures are: where the seismic fortification intensity is Degree 6~8, it shall meet the requirements of local seismic fortification intensity increased by 1; where the seismic fortification intensity is 8.1.7 In order to carry out static analysis, the following operations shall be carried out according to the data provided in the general drawing of boiler and by the other design department:
a) Determine the arrangement of column plane;
b) Determine the arrangement of vertical bracing;
c) Determine the elevation and arrangement of main plane of horizontal bracing; d) Perfect the arrangement of platform stairs;
e) Look up in the Contract and the Technical Agreement to meet the customer's demands; f) Count and distribute the load (action).
8.1.8 In order to reach the planned target, the arrangement and section of rod piece shall be adjusted during calculation process with the purpose of optimization.
8.1.9 The following drawing information shall be completed after the calculation result is confirmed to be reasonable and correct through analytical judgement:
a) Foundation load drawing. The plane position of column at 0m elevation and the vertical force, horizontal force and bending moment acted on the foundation under various working conditions shall be shown in the drawing.
b) Plan drawing of all vertical bracings. Generally, the interrelationship dimension of each member, beam elevation, column joint elevation, name and sectional dimension of column, name, sectional dimension and internal force of vertical bracing shall be marked in the drawing.
c) All horizontal plan drawings. Generally, the interrelationship dimension of each member, name and sectional dimension of beam, name, sectional dimension and internal force of horizontal bracing, beam end connection condition or the internal force required for calculation of beam end connection shall be marked in the drawing. d) Column section chart. Generally, column name, joint elevation and joint connection requirements and column section dimension shall be marked in the drawing. 8.2 Static analysis for boiler steel structure plane
8.2.1 In order to obtain the foundation load, determine the cross section of column and vertical bracing rod and the internal force of beam under load effect of vertical bracing plane, the vertical bracing plane shall be calculated.
a) The various permanent loads in and out of calculation plane and variable load shall be acted at the appropriate node of column in vertical bracing plane;
b) The wind load is distributed on the appropriate column node of horizontal bracing elevation in proportion according to the wind area;
c) The earthquake action shall be distributed to the appropriate column node of horizontal bracing elevation according to the height as required;
d) The expansibility, wind load and earthquake action of boiler guiding device are distributed on the appropriate column node of horizontal bracing elevation. 8.2.2 In order to determine the section of beam and horizontal bracing, the horizontal bracing plane shall be calculated.
a) The wind load is distributed on the appropriate column node in proportion according to the wind area;
b) The earthquake action shall be acted on each column node;
c) The expansibility, wind load and earthquake action of boiler guiding device shall be distributed on the appropriate node;
d) The braced force without vertical bracing column shall be acted on the appropriate position;
e) The vertical bracing point shall be regarded as the elastic fulcrum of horizontal bracing plane;
f) The beam section shall be determined according to the vertical load and axial force (the larger value of horizontal bracing calculation and vertical bracing calculation shall be taken) applied on the beam;
g) Each plane is calculated successively from bottom to top, and the detailed design, manufacture and installation may also be calculated successively from bottom to top. 8.2.3 The section of column without vertical bracing and the beam without horizontal bracing shall be determined according to the vertical load and bracing condition at end. 8.3 Static analysis for boiler steel structure space
8.3.1 The main characteristic of static analysis for boiler steel structure space is: the boiler steel structure and all the connected components are regarded as an interactional integrity, the calculation model is established according to the effective analytical simulation, the internal force and deformation of member is accurately calculated and then strength, rigidity and stability are checked.
8.3.2 The establishment of calculation model shall comply with load equivalent principle and load locality principle and the structure shall be reasonably simplified. a) Generally, calculation model is composed of column, vertical bracing, horizontal bracing, main beam and cantilever structure, the foundation usually is considered as rigid;
b) Cantilever structure may not be regarded as a part of model, in this case, the bending moment and horizontal force of cantilever structure at root point shall be considered. 8.3.3 Treatment of load and earthquake action:
a) Permanent load and variable load should be input according to the actual situation. b) Wind load shall be treated with different methods in accordance with the enclosed structure condition. Generally, if there is closed structure, the wind load should be automatically generated by the procedure; if there is no closed structure, besides considering the body wind load, the wind load of structure shall also be calculated. c) The manually treated earthquake action shall be redistributed according to the height (earthquake action of suspended boiler furnace body is not redistributed according to the height).
8.3.4 Checking calculation of braced force: the braced force working condition of horizontal truss adopted as column bracing point shall be checked and calculated. The braced force shall be determined according to 10.2.8.
8.3.5 Checking of column and beam: professional procedures are usually carried out for strength checking, but during checking of rigidity and stability, first order analysis procedures usually fail to correctly identify the calculation length of rod piece and the designer shall pretreat it in advance.
8.3.6 Integral structure rigidity: the arrangement of vertical bracing and horizontal bracing and rod piece section shall be regulated according to the spatial analysis result, to make the rigidity change of all storeys of structures to be uniform and avoid torsion or local large deformation of structure as possible.
9 Beam Design
9.1 Determination of beam sectional dimension
9.1.1 The beam section form is selected according to the load-bearing condition, connection mode, transportation and installation requirements.
9.1.2 Generally, the beam section form is I shape, box type and profile steel and compound section; box section should be selected for the torsion-bearing beam.
9.1.3 It?€?s generally designed as beam with uniform section, beam with variable section or stop log may be adopted for the large-span or large-load compound section.
Nv and Nt - the s...

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