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GB/T 50761-2018 English PDF (GBT50761-2018)

GB/T 50761-2018 English PDF (GBT50761-2018)

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GB/T 50761-2018: Standard for seismic design of petrochemical steel equipment

In order to implement the national laws and regulations on earthquake prevention and disaster reduction, implement a prevention-oriented policy, mitigate the seismic damage by seismic-fortifying the petrochemical equipment, reduce economic loss, this standard is hereby formulated. This standard is applicable to the seismic design of the petrochemical horizontal vessel, vertical vessels supported by legs, vertical vessels supported by lugs, vertical vessels supported by skirt, spherical tanks supported by legs, vertical cylindrical storage tanks, tubular heater, other steel equipment which are used in the area where the basic seismic acceleration not exceeding 0.40 g or seismic fortification intensity of 9 degrees or less.
GB/T 50761-2018
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
UDC
P GB/T 50761-2018
Standard for seismic design of
petrochemical steel equipment
ISSUED ON. JANUARY 16, 2018
IMPLEMENTED ON. SEPTEMBER 01, 2018
Issued by. Ministry of Housing and Urban-Rural Development of PRC;
General Administration of Quality Supervision, Inspection and
Quarantine of PRC.
Table of Contents
Foreword ... 6
1 General provisions ... 8
2 Terms and symbols ... 9
2.1 Terms ... 9
2.2 Symbols ... 10
3 Basic requirements ... 13
3.1 Classification of importance factors ... 13
3.2 Seismic influences ... 13
3.3 Equipment system design ... 14
4 Seismic action and seismic checking ... 16
4.1 General requirements ... 16
4.2 Seismic design response spectral of above-ground equipment ... 17
4.3 Horizontal seismic action of above-ground equipment ... 19
4.4 Horizontal seismic action of on-framework equipment ... 22
4.5 Vertical seismic action ... 23
4.6 Combination of loads ... 24
4.7 Seismic checking ... 25
5 Horizontal vessels ... 29
5.1 General requirements ... 29
5.2 Seismic action and seismic checking ... 29
5.3 Details of seismic design ... 30
6 Vertical vessels supported by legs ... 31
6.1 General requirements ... 31
6.2 Natural vibration period ... 31
6.3 Seismic action and seismic checking ... 33
6.4 Details of seismic design ... 33
7 Vertical vessels supported by lugs ... 34
7.1 General requirements ... 34
7.2 Natural vibration period ... 34
7.3 Seismic action and seismic checking ... 35
7.4 Details of seismic design ... 35
8 Vertical vessels supported by skirt ... 36
8.1 General requirements ... 36
8.2 Natural vibration period ... 36
8.3 Seismic action and seismic checking ... 38
8.4 Details of seismic design ... 39
9 Spherical tanks supported by legs ... 41
9.1 General requirements ... 41
9.2 Natural vibration period ... 41
9.3 Seismic action and seismic checking ... 44
9.4 Details of seismic design ... 45
10 Vertical cylindrical storage tanks ... 46
10.1 General requirements ... 46
10.2 Natural vibration period ... 46
10.3 Horizontal seismic action and seismic effect ... 47
10.4 Allowable compression longitudinal stresses of tank shell ... 49
10.5 Seismic checking of tank shell ... 49
10.6 Liquid sloshing height ... 52
10.7 Details of seismic design ... 53
11 Tubular heater ... 54
11.1 General requirements ... 54
11.2 Natural vibration period ... 54
11.3 Seismic action and seismic checking ... 60
11.4 Details of seismic design ... 62
Appendix A Horizontal seismic action of on-framework equipment ... 66
Appendix B Seismic checking of vertical vessels supported by legs ... 69 Appendix C Seismic checking of vertical vessels supported by lugs ... 75 Appendix D Calculation of flexible matrix element ... 79
Explanation of wording in this standard ... 83
List of quoted standards ... 84
Standard for seismic design of petrochemical steel
equipment
1 General provisions
1.0.1 In order to implement the national laws and regulations on earthquake prevention and disaster reduction, implement a prevention-oriented policy, mitigate the seismic damage by seismic-fortifying the petrochemical equipment, reduce economic loss, this standard is hereby formulated.
1.0.2 This standard is applicable to the seismic design of the petrochemical horizontal vessel, vertical vessels supported by legs, vertical vessels supported by lugs, vertical vessels supported by skirt, spherical tanks supported by legs, vertical cylindrical storage tanks, tubular heater, other steel equipment which are used in the area where the basic seismic acceleration not exceeding 0.40 g or seismic fortification intensity of 9 degrees or less.
1.0.3 For the petrochemical equipment which is subjected to the seismic design according to this standard, when it is impacted by the fortification earthquakes equivalent to the seismic fortification intensity of the area, the body, bracing member, anchoring structure shall not be damaged.
1.0.4 The design parameters of ground motion or the seismic fortification intensity shall be determined in accordance with the relevant provisions of the current national standard ?€?Seismic ground motion parameter zonation map of China?€? GB 18306. For the construction site where the seismic safety evaluation is completed, it shall carry out the seismic fortification according to the approved design parameters of ground motion or the seismic fortification intensity. 1.0.5 The seismic design of petrochemical steel equipment shall, in addition to complying with this standard, also comply with the relevant current national standards.
2 Terms and symbols
2.1 Terms
2.1.1 Seismic design
A specialized design for equipment that requires seismic fortification, including seismic calculations and seismic measures.
2.1.2 Seismic fortification intensity
The seismic intensity which is approved according to the authority as specified by the state as a basis for seismic fortification of a region.
2.1.3 Seismic action
The dynamic effects of equipment caused by ground motion, including
horizontal seismic action and vertical seismic action.
2.1.4 Seismic effect
Internal forces or deformations generated by the equipment under seismic action.
2.1.5 Design parameters of ground motion
The time-history curve of acceleration of ground motion, the response spectrum of acceleration, the peak acceleration which are used for seismic design. 2.1.6 Design basic acceleration of ground motion
The design value of the acceleration of ground motion which exceeds the probability of 10% in the 50-year design base period.
2.1.7 Characteristic period of ground motion
In the seismic influence factor curve for seismic design, the period value corresponding to the starting point of the falling segment which reflects the factors such as seismic magnitude, epicentral distance, site category, and other factors.
2.1.8 Seismic influence factor
The statistical mean of the ratio of the maximum acceleration response to the gravitational acceleration of a single-mass point elastic system under seismic action.
meq - The equivalent total mass of equipment;
mi, mj - Respectively, the masses concentrated on the particles i, j;
meqv - The vertical equivalent mass of equipment;
mi - The mass concentrated at the particle i;
mj - The mass concentrated at the particle j;
Sj - The effect produced by the horizontal seismic action of the vibration- mode j;
Sh - Horizontal seismic effect;
Xji - The horizontal relative displacement of the particle i of the jth vibration- mode.
2.2.2 Performance and resistance of materials.
Et - The modulus of elasticity of the material at the design temperature; Rel - The yield strength of material;
?? - The stress value under the action of load combination;
[??] - The allowable seismic stress of the material;
[??]t - The allowable stress of the material at the design temperature;
[??]b - The allowable seismic tensile stress of the material;
[??]bc - The allowable seismic compressive stress of the material;
?? - The value of the shear stress under the action of load combination; [??] - The allowable seismic shear stress of the material;
[??]b - The allowable seismic shear stress of the material.
2.2.3 Calculation coefficient.
??1 - The horizontal seismic action factor corresponding to the basic natural vibration period of the equipment or structure;
??j - The horizontal seismic action factor corresponding to the natural vibration period of the jth vibration-mode of the equipment;
??max - The maximum value of the horizontal seismic action factor;
4 Seismic action and seismic checking
4.1 General requirements
4.1.1 The seismic action and seismic checking of the equipment shall comply with the following provisions.
1. It shall calculate the seismic action in the horizontal direction and make seismic checking;
2. When the design basic acceleration of ground motion is 0.20 g ~ 0.40 g, or seismic fortification intensity is 8 degrees or 9 degrees, for the
horizontal vessel which has a diameter of more than 4 m and the spacing between two seats of more than 20 m, as well as the vertical vessels and the floor chimney of the tubular heater which have a height of more than 20 m, it shall calculate the vertical seismic action and make seismic
checking;
3. For the on-framework equipment, it shall take into account the seismic amplification of the structure in which the equipment is located.
4.1.2 When the design basic acceleration of ground motion is equal to 0.05 g or the seismic fortification intensity is 6 degrees, the category-1 and category- 2 equipment may not be subjected to the calculation of seismic action, but it shall meet the requirements for seismic measures.
4.1.3 For the seismic calculation of equipment, it should use the following methods.
1. The following equipment may use the bottom shear method.
1) The vertical vessel which has a height less than or equal to 10 m;
2) The vertical vessel which has an aspect ratio of less than 5 and a
relatively uniform distribution of mass and stiffness along the height
direction;
3) Equipment that can be simplified to a single-particle system.
2. Except for the equipment in item 1 of this clause, it should use the mode decomposition response spectrum method.
3. When the design basic acceleration of ground motion is more than or
equal to 0.30 g, the vertical vessel which has an aspect ratio of more than 120 m and the vertical cylindrical storage tanks which are more than 15 x 104 m3 should be supplemented by time-history analysis.
Fhji - The design value of the horizontal seismic action at the particle i of the jth vibration-mode (N);
??j - The horizontal seismic influence factor corresponding to the natural vibration period of the jth vibration-mode of the equipment, which is
determined according to the provisions of clause 4.2 of this standard;
??j - The participation factor of the jth vibration-mode;
Xji - The horizontal relative displacement at the particle i of the jth vibration- mode.
2. The horizontal seismic effect shall be determined as follows.
Where.
Sh - The horizontal seismic effect;
Sj - The effect produced by the horizontal seismic action of the jth vibration- mode, taking the first 2nd ~ 3rd vibration-mode. When the basic natural vibration period is greater than 1.5 s, the number of vibration-modes is not less than 3.
4.4 Horizontal seismic action of on-framework equipment
4.4.1 When the mass ratio of the framework to the equipment is more than or equal to 2, the horizontal seismic action of the equipment should be calculated in accordance with the provisions of this clause.
4.4.2 The design value of the horizontal seismic action of on-framework equipment may be calculated as follows.
Where.
Fhk - The design value of horizontal seismic action of on-framework
equipment (N);
Km - The amplification factor of seismic action of on-framework equipment, which is selected according to Table 4.4.2.
5. Design value of horizontal and vertical seismic action;
6. Snow load, considering the combination factor of 0.5, which takes 0 for high-temperature parts and for the small load-bearing surface of
equipment;
7. Other loads, including the reaction force of the seat, the base ring, the lugs and other types of supports, the force of the connecting pipeline and other components, the force caused by the difference in temperature gradient
or thermal expansion, etc.;
8. Live loads, including major moving loads such as people, tools, repairs, shocks, vibrations, etc.
4.7 Seismic checking
4.7.1 When using the limit state design, it shall carry out seismic checking according to the relevant provisions of the current national standard ?€?Code for seismic design of buildings?€? GB 50011.
4.7.2 When using the allowable stress design, it shall carry out seismic checking according to the following provisions.
1. When the equipment is subjected to seismic checking, the stress value of the checked part under the action of load combination shall meet the
requirements of the following formula.
Where.
?? - The stress value under the combination of loads (MPa);
?? - Welded joint factor, which takes 1.0 when compressed;
[??] - Seismic allowable stress of the material (MPa);
?? - Shear stress value under combination of loads (MPa);
[??] - Seismic allowable shear stress of the material (MPa).
2. The allowable stress for seismic checking of equipment shall be
determined in accordance with the following provisions.
1) The body and bearing member may be calculated as follows.
5 Horizontal vessels
5.1 General requirements
5.1.1 The seismic design of horizontal vessel shall comply with the provisions of this clause.
5.1.2 The basic natural vibration period of horizontal vessel may be taken as 0.10 s; when multiple vessels overlap, the basic natural vibration period may be 0.15 s.
5.2 Seismic action and seismic checking
5.2.1 For the calculation of horizontal seismic action of horizontal vessel, the seismic influence factor may be taken as the maximum value according to the provisions of clause 4.2.1 of this standard.
5.2.2 For the horizontal vessels installed above-ground, it shall follow the requirements of clause 4.3 of this standard to respectively calculate its axial and lateral seismic actions. For the on-framework horizontal vessels, it may follow the requirements of clause 4.4 of this standard to respectively calculate its axial and lateral seismic action.
5.2.3 The damping ratio of horizontal vessel may be 0.05.
5.2.4 For overlapping horizontal vessels, both axial and lateral directions can be regarded as a multi-degree-of-freedom system (Figure 5.2.4). The seismic action of overlapping horizontal vessels installed above-ground may be
calculated according to the clause 4.3 of this standard. The seismic influence factor may be taken as the maximum value of the horizontal seismic influence factor; the total seismic action of the overlapping on-framework horizontal vessels and the horizontal seismic action of each particle may be calculated according to clause 4.4 of this standard.
h - The height from the foundation?€?s top surface to the centroid of the equipment (mm).
6.3 Seismic action and seismic checking
6.3.1 For the calculation of horizontal seismic action of vertical vessels supported by legs, the seismic influence factor shall comply with the provisions of clause 4.2 of this standard for the fortified earthquakes.
6.3.2 The seismic action of the vertical vessels supported by legs installed above-ground shall be calculated in accordance with clause 4.3.1 of this standard; the seismic action of the vertical vessels supported by legs installed on-framework shall be calculated in accordance with clause 4.4 of this standard. 6.3.3 The damping ratio of the vertical vessels supported by legs may be 0.05. 6.3.4 The seismic checking of the casings, legs, connecting weld between legs and cylinder, anchor bolts, etc. of vertical vessels supported by legs shall comply with the provisions of clause 4.7 of this standard.
6.3.5 The seismic checking method for vertical vessels supported by legs can be carried out in accordance with the provisions of Appendix B of this standard. 6.4 Details of seismic design
6.4.1 The number of legs shall not be less than 3, the fortification intensity shall be 8 degrees or 9 degrees. When the diameter of the equipment is more than 800 mm, the number of legs should not be less than 4.
6.4.2 Each leg shall be provided with anchor bolts. The diameter of the bolts should not be less than M16. The nuts shall be provided with anti-loose measures.
8 Vertical vessels supported by skirt
8.1 General requirements
8.1.1 The seismic design of the vertical vessels supported by skirt shall comply with the provisions of this clause.
8.1.2 When the height is greater than 20 m and the design basic acceleration of ground motion is greater than or equal to 0.20 g or the seismic fortification intensity is 8 degrees and 9 degrees, it shall take into account of the influence of the vertical seismic action.
8.2 Natural vibration period
8.2.1 The vertical vessels supported by skirt can be simplified to a multi-particle system to calculate the natural vibration period.
8.2.2 For the equal-diameter and equal-thickness vertical vessels supported by skirt installed on the ground foundation, the basic natural vibration period may be calculated as follows.
Where.
T1 - The basic natural vibration period of the equipment (s);
H - The height from the foundation?€?s top surface to the equipment?€?s top (mm); m0 - The total mass of the equipment (kg);
Et - The modulus of elasticity of the material (MPa);
Di - The inner diameter of the cylinder of the equipment (mm);
??e - The effective thickness of the cylinder of the equipment (mm).
8.2.3 For the unequal-diameter or unequal-thickness floor-standing vertical vessel, it may consider the equipment whose diameter, thickness, material changes along height into a multi-particle system (Figure 8.2.3). The basic natural vibration period may be calculated according to the following formula. influence factor may take the maximum value of the horizontal seismic influence factor of the fortified earthquake.
8.3.4 For the vertical vessel supported by skirt which has a height of more than 10 m and an aspect ratio of more than 5, it may use the vibration-mode
decomposition method for calculation.
8.3.5 The damping ratio of the vertical vessel supported by skirt may be determined as follows.
1. When the basic natural vibration period of the equipment is less than or equal to 1.5 s, it may take 0.035.
2. When the basic natural vibration period of the equipment is more than 1.5 s and less than or equal to 2.0 s, it may be calculated as follows.
3. When the basic natural vibration period of the equipment is more than 2.0 s, it may take 0.01.
8.3.6 The vertical seismic action of the vertical vessel supported by skirt shall be calculated in accordance with the provisions of clause 4.5 of this standard. 8.3.7 The casing, the skirt cylinder, the foundation ring, the anchor bolt seat, the connecting weld of skirt and casing, the connecting weld of bolt seat and skirt cylinder, the anchor bolts of the vertical vessel supported by skirt shall be subjected to seismic checking, meanwhile it shall comply with the provisions of clause 4.7 of this standard.
8.4 Details of seismic design
8.4.1 The platform of the equipment should not be directly connected to other equipment or structures.
8.4.2 The heavier auxiliary equipment outside the equipment should be
provided with a separate bracing structure, which should not be directly braced by the equipment.
8.4.3 The internal load-bearing members of the equipment shall be securely connected to the casing.
8.4.4 When the aspect ratio of the equipment is more than 5 and the seismic fortification intensity is greater than 7 degrees, the equipment?€?s cylinder should not be overlapped with the skirt seat.
9 Spherical tanks supported by legs
9.1 General requirements
9.1.1 The seismi...

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