GB 50009-2001 - 2006 Load Code for the Building Design, China

NATIONAL STANDARD OF

GB

THE PEOPLE’S REPUBLIC OF CHINA 中华人民共和国国家标准 GB 50009-2001

Load Code for the Design of Building Structures

建筑结构荷载规范 (2006 Edition)

Issued on January 10, 2002 Jointly Issued by

Implemented on March 01, 2002

the Ministry of Construction (MOC) and the General Administration of Quality Supervision, Inspection and Quarantine (GAQSIQ) of the People’s Republic of China

Notice of Issuing Load Code for the Design of Building Structures JIANBIAO [2002] No.10 In accordance with Notice of Printing and Distributing the Establishment and Amendment Plan of Project Construction Standard of 1997 (JIANBIAO [1997] No.108) issued by the Ministry of Construction, the Load Code for the Design of Building Structures jointly developed by the Ministry of Construction and related departments has been authorized by related departments as a national standard, with the number of GB 50009- 2001 and will be implemented from March 1, 2002. Among which, articles 1.0.5, 3.1.2, 3.2.3, 3.2.5, 4.1.1, 4.1.2, 4.3.1, 4.5.1, 4.5.2, 6.1.1, 6.1.2, 7.1.1 and 7.1.2 are compulsory ones and shall be executed strictly. At the same time, the original Load Code for Building Structures (GBJ9-87) shall be terminated on December 31, 2002. The Code is in the charge of the Ministry of Construction that is responsible for the interpretation of compulsory articles. The China Architecture Research Institute will be responsible for the interpretation of technical contents. In addition, the Code shall be published by China Architecture & Building Press (CABP) with the organization of Research institute of Standards & Norms. Ministry of Construction P. R. China July 20, 2001

Foreword This Code has been overall revised in accordance with Notice of Printing and Distributing of the Establishment and Amendment of Building Construction of 1997 (JIANBIAO [1997] No.108) issued by the Ministry of Construction and the Load Code for the Design of Building Structures (GBJ 9-87) jointly approved by China Architecture Scientific Research Institute and related departments. During the process of revising, the team has carried out monographic study, summarized design experience in recent years, referred to related contents of foreign norms and international standards, widely asked for opinions from related departments all over the country and finalized after repeated amendment. This Code can be divided into seven chapters and seven appendices. Primary contents revised are as follows: 1. In accordance with the rule of combination stated in Unified Standard for Reliability Design of Building Structures and getting rid of Wind Combination, the combination controlled by permanent load effect was added to the load fundamental combination. In the limit design of regular service, for the short-term effect combination, characteristic and frequent combinations are listed and at the same time, the frequent value coefficient was added to the variable load. For all combination values of variable loads, respective combination value coefficient is listed. 2. Partial adjustment and amendment of floor live load. 3. Adjustment has been made to roofing rectangular distribution live load that permits no person on the roof and provisions on roof gardens and helicopter pad load have been added. 4. Character of service for crane has been changed into work classes of cranes. 5. According to new observation data, statistics of wind pressure and snow pressure from national weather stations has been collected. At the same time, the basic value of wind and snow load recurrence interval has been changed from 30 years to 50 years. In the appendix, the 10-year, 50-year and 100-year wind pressure and snow pressure in main stations all over the country have been listed. 6. One Type has been added to the terrain roughness. 7. For the wind pressure altitude variation coefficient of buildings in a mountainous area, compensation factors have been given for the consideration of terrain conditions. 8. Specific provisions have been made to wind load of envelop enclosure members. 9. The interactive influences between buildings in architectural complex have been put forward. 10. For flexible structures, the test requirements for crosswind vibration have been added. This Code may be revised as required. Information and contents revised will be published on the journal of Standardization of Engineering Constructions. The compulsory articles in this Code shall be executed strictly. In order to improve the quality of this Code, units shall sum up experience and collect background information. For feedback of related opinions and suggestions, please contact: China Architecture Scientific Research Institute (No.30 East Road, North Third Ring). Chief Development Organization: China Architecture Technical Research Institute Participating Development Organizations: Construction Department of Tongji University,

Building Design Institute, Beijing International Design Institute of China Light Industry, Beijing: China Institute of Architecture Standard Design Press, Beijing Institute of Architectural Design and China Weather Scientific Research Institute Chief Drafting Staffs: Chen Jifa, Hu Dexin, Jin Xinyang, Zhang Xiangting, Gu Zicong, Wei Caiang, Cai Yiyang, Guan Guixue, Xue Hang

Contents 1. General Principles ................................................................................................................. 1 2. Terms and symbols ................................................................................................................ 1 2.1 Terms ........................................................................................................................... 1 2.2 Main symbols............................................................................................................... 3 3. Classification of loads and combination of load effect ......................................................... 4 3.1 Classification of loads and representative values of a load ......................................... 4 3.2 Load combination ........................................................................................................ 5 4. Live load of floors and roofs ................................................................................................. 7 4.1 Rectangular distribution live load on floors of civilian buildings ............................... 7 4.2 Floor live load of industrial buildings........................................................................ 10 4.3 Roof live load............................................................................................................. 10 4.4 Roofing dust load........................................................................................................11 4.5 Construction and repair load as well as handrail horizontal load .............................. 13 4.6 Dynamic coefficient................................................................................................... 14 5. Crane load............................................................................................................................ 14 5.1 Vertical and horizontal load of cranes........................................................................ 14 5.2 The combination of several cranes ............................................................................ 15 5.3 Dynamic coefficient of crane loads ........................................................................... 15 5.4 The combination value, frequent value and quasi-permanent value of crane loads .. 15 6. Snow load ............................................................................................................................ 16 6.1 The characteristic value/nominal value and reference snow pressure of snow loads 16 6.2 Coefficient of snow distribution over the roof........................................................... 17 7. Wind load ............................................................................................................................ 20 7.1 The characteristic value/nominal value and reference wind pressure of wind loads . 20 7.2 Variation coefficient of wind pressure altitude .......................................................... 21 7.3 Wind load coefficient................................................................................................. 22 7.4 Downwind vibration and wind vibration coefficient ................................................. 36 7.5 Gustiness factor.......................................................................................................... 38 7.6 Crosswind vibration................................................................................................... 39 Appendix A Deadweight of Commonly-used Materials and Members................................... 41 Appendix B Method for Deciding the Floor Isoeffect Rectangular Distribution Live Load... 55 Appendix C Floor live load of industrial buildings................................................................. 60 Appendix D Measurement Method of Fundamental Snow Pressure and Wind Pressure........ 66 Appendix E Empirical Formula for the Structure Which is Natural Vibration Period .......... 108 Appendix F Approximation of the Structural Mode Factor....................................................111 Appendix G Wording Explanation .........................................................................................113

1. General Principles 1.0.1 This Code is designed to meet demands in building structure design and requirements of secure application and economic feasibility. 1.0.2 This Code is applicable to the building structure design. 1.0.3 This Code has been made in accordance with principles stated in Unified Standard for Reliability Design of Building Structures (GB 50068-2001). 1.0.4 Effects involved with the building structure design include direct effect (combination of loads) and indirect effect (including subbase deformation, concrete shrinkage, welding deformations, temperature fluctuation or effects caused by earthquakes). In this Code, only provisions on combination of loads are stated. 1.0.5 The design reference period adopted in this Code is 50 years. 1.0.6 Effects or combination of loads involved with the building structure design shall be in accordance with this Code as well as other current national provisions.

2. Terms and symbols 2.1 Terms 2.1.1 Permanent load During the utilization period of structures, the value of the combination of loads shall have no change with the passage of time or the variation is negligible compared with the average, or the variation is monotonous and tends to the limitation. 2.1.2 Variable load During the utilization period of structures, the value of combination of loads shall be changed with the passage of time and the variation is negligible compared with the average. 2.1.3 Accidental load During the utilization period of the structure, the combination of loads does not necessarily appear, but one it appears, the value is great but the duration is short. 2.1.4 Representative values of a load The value of combination of loads adopted during the design for the checking of limiting state, such as characteristic value/nominal value, combination value, frequent value and quasi- permanent value. 2.1.5 Design reference period The time parameter selected for deciding the representative value of the variable load. 2.1.6 Characteristic value/nominal value The basic representative value of loads refers to the maximum characteristic value (such as typical value, mode, median or some place value) of statistical distribution of loads in the design reference period. 2.1.7 Combination value 1

The value of combination of loads that makes the load effect exceed probability during the design reference period and make the solitude appearance of the combination of loads has a unified value of combination of loads or make the structure has unified value of combination of loads with reliability index stated in the provision. 2.1.8 Frequent value For variable load, during the design reference period, the exceeded total time is the minimum ratio or the exceeded frequency is the value of the combination of loads of the assigned frequency. 2.1.9 Quasi- permanent value For variable load, during the design reference period, the exceeded total time is about half of the value of combination of loads in the design reference period. 2.1.10 Design value of a load The arithmetic product of the representative values of a load and the partial load factor. 2.1.11 Load effect Reaction of structures or structural elements caused by the combination of loads, such as internal force, distortion and crack 2.1.12 Load combination In the limit design, to guarantee the built-in reliability, provisions for all kinds of design values of a load have been made. 2.1.13 Fundamental combination In the limit of bearing capacity state, the combination of permanent effect and variable effect 2.1.14 Accidental combination In the limit of bearing capacity state, the combination of permanent effect, variable effect and an accidental combination 2.1.15 Characteristic/nominal combination In the regular service limiting state, the characteristic value/nominal value or combination value adopted is the combination of representative values of a load. 2.1.16 Frequent combinations In the regular service limiting state, the frequent value or permanent value is adopted in the variable load is the combination of representative values of a load. 2.1.17 Quasi- permanent combinations In the regular service limiting state, the quasi- permanent value adopted by the variable load is the combination of the representative values of a load. 2.1.18 Equivalent uniform live load During the structure design, the actual load of continuous distribution above or under the floor is always by substituted by the evenly distributed load. The equivalent uniform live load refers to the load effect received by the structure can keep in line with the evenly distributed load of the actual load effect. 2.1.19 Tributary area The tributary area is adopted during the calculation of the beam column members. It refers to the floor space of the calculated member load. It shall be divided by the zero line of the floor slab. In the practical situation, it can be simplified. 2.1.20 Dynamic coefficient 2

Structures and members that receives dynamic load, when designed according to the static force, shall adopt the value that is the ratio of the maximum power effect of structures or members and relevant static force effect. 2.1.21 Reference snow pressure The reference pressure of snow load shall be decided by the maximum value of the 50-year period calculated from the probability statistics according to the observation data from the deadweight of snow on the local open and equitable terrain. 2.1.22 Reference wind pressure The reference pressure of wind load shall be decided by the maximum wind speed for a 50-year period calculated from the probability statistics according to the observation data of average speed in 10min at 10m on the local open and equitable terrain. Also, relevant air density shall be considered and the wind pressure shall be calculated according to the formula (D.2.2-4). 2.1.23 Terrain roughness When the wind passes 2km range before reaching the structure, the class used to describe the distribution pattern of irregular barriers on the ground. 2.2 Main symbols Gk——characteristic value/nominal value of permanent load; Qk——characteristic value/nominal value of variable load; GGk——characteristic value/nominal value of permanent load effect; SQk——characteristic value/nominal value of the variable load effect; S——load effect combination design value; R——The design value of resisting power of structural members; SA——Downwind load effect; SC——Crosswind load effect; T——Natural vibration period of structures; H——Top height of structures; B——Windward width of structures; Re——Reynolds number; St——Strouhai number; sk——Characteristic value/nominal value of snow load; s0——reference snow pressure; wk——characteristic value/nominal value of wind load; w0——reference wind pressure; νcr——Critical wind velocity of crosswind sympathetic vibration; α——Angle of gradient; βz——Gust coefficient at height Z; βgz——Gust coefficient at height Z; γ0——Structure significance coefficient; γG——Subentry coefficient of permanent load; γQ——Subentry coefficient of variable load; ψc——combination value coefficient of the variable load; 3

ψf——frequent value coefficient of variable load; ψq——quasi-permanent value coefficient of variable load; µr——Coefficient of snow distribution over the roof µz——Variation coefficient of wind pressure altitude; µs——Wind load coefficient; η——Coefficient of wind load terrain and physiognomy amendment; ξ——Aggrandizement coefficient of wind load pulsation; ν——Impact coefficient of wind load pulsation; φz——Structural vibration mode coefficient; ζ——Structural damping ratio.

3. Classification of loads and combination of load effect 3.1 Classification of loads and representative values of a load 3.1.1 The structural combination of loads can be divided into three kinds: 1. Permanent load, such as dead load, earth pressure and prestress. 2. Variable load, such as floor live load, roof live load and dust load, crane load, wind load and snow load. 3. Accidental load, such as blasting power and force of percussion. Note: Deadweight refers to the combination of loads (gravitation) caused by the weight of materials.

3.1.2 During the design of building structures, different combinations of loads shall adopt different representative values. For permanent loads, the representative value shall be the characteristic value/nominal value. While for variable loads, the representative value shall be the characteristic value/nominal value, combination value, frequent value or quasi- permanent value according to different design requirements. For accidental loads, the representative value shall be decided according to the utilization characteristics of building structures. 3.1.3 Permanent load characteristic value/nominal value: for structural deadweight, it shall be decided according to the design size of structural members and the deadweight of unit volume of materials; for commonly-used materials and members, it shall be decided according to appendix 1 of this Code; for materials and members (including field fabricated heat insulators, concrete thin-wall members) with major changes in deadweight, it shall be the upper value or the lower range value according to the advantage or disadvantage state to members. Note: For commonly-used materials and members, refer to Appendix A.

3.1.4 The characteristic value/nominal value of variable loads shall be adopted according to provisions in this Code. 3.1.5 The design of limit of bearing capacity state or the regular service limiting state shall adopt the combination value as the representative value of the variable loads. The combination value of variable loads refers to the variable load characteristic value/nominal value multiplied by the combination value coefficient of combination of loads. 3.1.6 If the regular service limiting state is designed according to the frequent combinations, 4

the frequent value, quasi-permanent value shall be adopted as the representative value. If it is designed according to the quasi-permanent combinations, the quasi-permanent value shall be adopted as the representative value of variable loads. The frequent value of variable loads shall adopt the variable load characteristic value/nominal value multiplied by the frequent value coefficient of combination of loads. The variable load quasi- permanent value shall adopt the characteristic value/nominal value of variable loads multiplied by the quasi-permanent value coefficient of combination of loads. 3.2 Load combination 3.2.1 The design of building structures shall be in accordance with the combination of loads arising in the construction during the utilization process, according to the limit of bearing capacity state and the regular service limiting state. The design shall take the most disadvantaged combination for the combination of loads (effect). 3.2.2 For the limit of bearing capacity state, the combination of loads (effect) shall adopt the fundamental combination or accidental combination of load effect. The following design expression shall be adopted: γ0S ≤R (3.2.2) Where, γ0——Structure significance coefficient; S——The design of load effect combination; R——The design value of resisting power of structural members shall be decided by related design specifications of building structures. 3.2.3 For the design value (S) of the fundamental combination of loads and load effect, it shall be decided by the most disadvantaged value from the following combination values: 1) Combination controlled by the variable load effect;

(3.2.3-1) Where, γG——Subentry coefficient of permanent load shall be adopted according to Article 3.2.5. γQi——The ith subentry coefficient of variable load. γQi is the subentry coefficient of variable load Q1, to be adopted according to Article 3.2.5. SGk——The load effect value calculated according to the permanent load characteristic value/nominal value Gk; SQik——The load effect value calculated according to variable load characteristic value/nominal value Qik. SQ1k is the controller of all variable load effects. ψci——The combination value coefficient of the variable load Qi shall be adopted according to provisions in chapters. n——The number of variable loads forming the combination. 2) Combination controlled by the permanent load effect:

5

(3.2.3-2) Note: 1 The design value of fundamental combination is applicable to the linear load effect. 2. If the SQ1k can't be decided distinctively, each variable load effect shall be taken as SQ1k and the most disadvantaged load effect combination shall be selected.

3.2.4 For common bents and frame structures, the reduction rule may be adopted in the fundamental combination and the most disadvantaged value shall be selected according to the following combination values: 1) Combination controlled by variable load effect;

(3.2.4) 2) The combination controlled by the permanent load effect shall be adopted according to formula (3.2.3-2). 3.2.5 The subentry coefficient of combination of loads in the fundamental combination shall be adopted according to the following provisions: 1. Subentry coefficient of permanent load; 1) If the effect causes disadvantages to the structure, ——for the combination controlled by the variable load effect, select 1.2; ——for the combination controlled by the permanent load effect, select 1.35. 2) If the effect causes advantages to the structure, select 1.0. 2. Subentry coefficient of variable load: ——Generally, select 1.4; ——For the characteristic value/nominal value of the live load of industrial housing floor greater than 4kN/m2, select 1.3. 3. For the overturn, slippage or floating calculation, the load subentry coefficient shall be adopted according to provisions in related design codes for structures. 3.2.6 For the design value of accidental combination and load effect combination, it shall be in accordance with the following provisions: the representative value of the accidental loads doesn't multiply subentry coefficient; if it appears together with the accidental loads and other combinations of loads, the representative value shall be adopted according to the observational data and project experience. Under different circumstances, the formula of design value of the load effect shall be decided by contrary provisions. 3.2.7 In the regular service limiting state, according to different design requirement, the characteristic/nominal combination, frequent combinations or quasi-permanent combinations may be adopted and the design shall be carried out according to the following design expression: S≤C (3.2.7) Where, C——The limitation of structures or structural members when they are in regular service, such as the limitation of distortion, crack, amplitude, acceleration and stress, shall be adopted 6

according to related design codes for building structures. 3.2.8 The design value (S) characteristic/nominal combination and load effect combinations shall be adopted according to the following formula:

(3.2.8) Note: The design value of the combination is applicable to the linear combination of loads and load effect.

3.2.9 The design value (S) of frequent combinations and load effect combinations shall be adopted according to the following formula:

(3.2.9) Where, ψf1——The frequent coefficient of variable load Q1 shall be adopted according to provisions in chapters. ψqi——The quasi value coefficient of the variable load Qi shall be adopted according to provisions in chapters. Note: The design value of the combination is applicable to the linear combination of loads and load effect.

3.2.10 The design value (S) of quasi-permanent combinations and load effect combinations shall be adopted according to the following formula:

(3.2.10) Note: The design value of the combination is applicable to the linear combination of loads and load effect.

4. Live load of floors and roofs 4.1 Rectangular distribution live load on floors of civilian buildings 4.1.1 The characteristic value/nominal value, combination value, frequent value and quasi-permanent value coefficient of the rectangular distribution live load on floors of civilian buildings shall be adopted according to Table 4.1.1.

7

Table 4.1.1 the characteristic value/nominal value, combination value, frequent value and quasi-permanent value coefficient of rectangular distribution live load on floors of civilian buildings Item

Type

Characteristic

Combination

Frequent

Quasi-permanent

value/nominal

value

value

value coefficient

value (kN/m2)

coefficient ψc

coefficient ψf

ψq

0.5

0.4

2.0

0.7 0.6

0.5

(1) Residential buildings, dormitories, hotels, office buildings, hospital wards, nursery and 1

kindergarten; (2) Schoolrooms, testing labs, reading rooms, boardrooms, policlinic rooms of hospitals.

2

Dining

restaurant,

archives

for

playhouse,

cinema

and

2.5

0.7

0.6

0.5

3.0

0.7

0.5

0.3

3.0

0.7

0.6

0.5

3.5

0.7

0.6

0.5

(2) Bleachers without fixed seats.

3.5

0.7

0.5

0.3

(1) Gymnasia and stages for performance;

4.0

0.7

0.6

0.5

(2) Ballrooms.

4.0

0.7

0.6

0.3

0.9

0.9

0.8

7.0

0.9

0.9

0.8

(1) 3

rooms,

general materials; Auditoria,

bleachers with fixed seats; (2) Public laundries. (1) Stores, exhibition halls, stations, ports,

4

5

airport halls and waiting rooms;

(1) Stack rooms, archival repository and 6

store rooms; (2) Stack rooms with dense tanks.

7

5.0 12.0

Fan houses and elevator towers Automobile passages and parking rooms: (1) one-way slab building covers (the span no less than 2m) Carriages; Fire-fighting vehicles;

8

(2) Two-way slab building covers (the span

4.0

0.7

0.7

0.6

35.0

0.7

0.7

0.6

no less than 6m*6m) and flat slab floor (the dimension of column grids no less than 6m *

2.5

0.7

0.7

0.6

20.0

0.7

0.7

0.6

Kitchen (1) Ordinary;

2.0

0.7

0.6

0.5

(2) Restaurant.

4.0

0.7

0.7

0.7

(1) Civilian building in item 1;

2.0

0.7

0.5

0.4

(2) Other civilian buildings.

2.5

0.7

0.6

0.5

2.0

0.7

0.5

0.4

2.5

0.7

0.6

0.5

3.5

0.7

0.5

0.3

(1) In common situation;

2.5

0.7

0.6

0.5

(2) People may be gathering.

3.5

6m) Carriages; Fire-fighting vehicles. 9

Bathrooms, toilets and wash rooms: 10

Corridors, hallways, staircases: (1) Dormitories, hotels, hospital wards, nursery, 11

kindergarten

and

residential

buildings; (2)

Office

buildings,

schoolrooms,

restaurants, policlinic of hospitals; (3) Fire-control fire escapes and other civilian buildings. Balcony: 12

8

Note: 1.

All live loads in this Table are applicable for natural service conditions. If the working load is extremely large,

the live loads shall be adopted according to practical situations. 2. for the live load of stack rooms in item 6, if the height of bookshelves is greater than 2 m, the live load for stack rooms shall be decided according to a height no less than 2.5kN/m2. 3. The live load for carriages in item 8 is applicable to carriages holding fewer than 9 persons. The live load of fire-fighting vehicles is applicable to oversize vehicles with the full load of 300kN. If requirements in this Table are not met, according to the equivalence principle of structural effect, the partial load of wheels shall be converted to the equivalent uniform live load. 4. The live load for staircases in item 11, for the precast stair footfall slabs, shall be calculated according to a concentrated load of 1.5kN. 5. All combinations of loads do not contain the deadweight of partitions and the combination of loads for the second fixture and fitting. The fixed partition and deadweight shall be taken as permanent combination of loads. If the position of partitions can be moved freely, the weight of non-fixed partitions shall take 1/3 the weight of the wall as the additive value (kN/m2) which shall be no less than 1.0 kN/m2 of the live loads on floors.

4.1.2 For the design of girders, walls, columns and foundations of floors, under the following circumstances, the characteristic value/nominal value of live loads on the floors in Table 4.1.1 shall be multiplied by the discount coefficient: 1. The discount coefficient during the design of floor girders; 1) In item 1(1), if the tributary area of girders exceeds 25m2, select 0.9; 2) In items 1(2)-7, if the tributary area of girders exceeds 50m2, select 0.9; 3) In item 8, junior beam of one-way slabs and vittae of trough plates, select 0.9; For girder of one-way slabs, select 0.6; For girders of two-way slabs, select 0.8. 4) For items 9-12, the discount coefficient shall be the same as that of the buildings. 2. The discount coefficient of designing walls, columns and foundations: 1) Item 1(1) shall be adopted according to Table 4.1.2. 2) Items 1(2)-7 shall adopt the discount coefficient the same as that of the girders of floors. 3) In item 8, for one-way slabs, select 0.5; For two-way slabs and flat slab floors, select 0.8. 4) In items 9-12, the discount coefficient shall be adopted the same as that of the building. Note: The tributary area of floor girders is decided by the real area within the range extending 1/2 case bay to both sides of the girder.

Table 4.1.2 Discount coefficient of live loads according to different floors Number of floors above the calculation section of walls, volumes and foundations

1

2-3

4-5

6-8

9-20 ≥20

The discount coefficient of live loads total on each floor above the calculation section

1.00 (0.90)

0.85 0.70 0.65 0.60 0.55

Note: If the tributary area of floor girders exceeds 25m2, the coefficient shall adopt the one in the parentheses.

4.1.3 The partial loads on floor structures shall be converted into isoeffect rectangular distribution live loads according to Appendix B.

9

4.2 Floor live load of industrial buildings 4.2.1 During the production utilization or the installation repair of floors of industrial buildings, the partial load produced by the equipment, pipelines, transportation tools or possibly-removed partitions shall be considered according to the practical situation and can be substituted by the isoeffect rectangular distribution live load. Note: 1. The floor isoeffect rectangular distribution live load shall be decided by the method stated in Appendix B. 2. For common smith shops, instrumentation production workshops, semiconductor device workshops, cotton spinning and knitting workshops, preparing shops in tire plants and grain processing workshops, if there are not enough materials; it shall be adopted according to Appendix C.

4.2.2 The operation combination of loads, including operating personnel, general purpose tools, small amount of raw materials and the deadweight of finished products on areas without equipment of floors ( including working platforms) of industrial buildings shall be considered as the rectangular distribution live load and adopt 2.0kN/m2. The staircase live load in production workshops shall be adopted according to the practical situation and shall be no less than 3.5kN/m2. 4.2.3 The combination value coefficient, frequent value coefficient and quasi- permanent value coefficient of floor live loads of industrial buildings shall be adopted according to the practical situation besides values given in Appendix C. However, under no circumstance shall the combination value and the frequent value coefficient be less than 0.7 and the quasi-permanent value coefficient no less than 0.6. 4.3 Roof live load 4.3.1 The roof rectangular distribution live load on the horizontal projection surface shall be adopted according to Table 4.3.1. The roof rectangular distribution live load can't be considered together with the snow load. Table 4.3.1 Roof rectangular distribution live load Characteristic Item

Type

Combination value

Frequent value

Quasi-permanent value

coefficient ψc

coefficient ψf

coefficient ψq

0.5

0.7

0.5

0

2.0

0.7

0.5

0.4

3.0

0.7

0.6

0.5

value/nominal value (kN/m2)

1

2 3

Roof without holding persons Roof holding persons Roof garden

Note: 1. For roofs without holding persons, if the construction load is comparatively large, it shall be adopted according to the practical situation. For different structures, according to related design specifications, the characteristic value/nominal value shall be increased or decreased by 0.2kN/m2. 2. For roofs holding persons, if they are used for other purposes, relevant floor live loads shall be adopted. 3. For seeper combination of loads caused by the disturbance of roof drainage or blockage, construction measures shall be adopted. If necessary, the roof live loads shall be decided according the possible depth of

10

seepers. 4. The live load on roof gardens does not include the material deadweight of earth materials.

4.3.2 The combination of loads of parking apron for helicopters shall be considered as the partial load according to the gross weight of the helicopter. At the same time, its isoeffect shall be no lower than 5.0kN/m2. The partial load shall be decided according to the practical maximum lifting loads of helicopters. If there is no technical information of aircraft types, commonly, the partial load characteristic value/nominal value and active area shall be selected according to various requirements of light, medium and heavy types: ——Light-type: the maximum take-off weight is 2t, partial load characteristic value/nominal value is 20kN and the active area is 0.20m * 0.20m. ——Medium-type: the maximum take-off weight is 4t, partial load characteristic value/nominal value is 40kN and the active area is 0.25m * 0.25m. ——Heavy-type: the maximum take-off weight is 6t, the partial load characteristic value/nominal value is 60kN and the active area is 0.30m * 0.30m. The combination value coefficient of loads shall be 0.7, the frequent value coefficient 0.6 and the quasi-permanent value coefficient shall be 0. 4.4 Roofing dust load 4.4.1 During the design of workshops that release mass dust and their neighboring buildings, for roofs of machinery, cement and metallurgy workshops with certain dedusting facilities, the roof dust load on the horizontal projection surface shall be adopted according to Table 4.4.1-1 and 4.4.1-2.

11

Table 4.4.1-1 Roof dust load Characteristic value/nominal value Combination

(kN/m2) Item

Type

Roofs without breastplate

1 2 3

4

5

6

Foundry in machinery plants ( cupola) Melting house ( oxygen converter) Manganese and ferrochrome workshops Silicon and ferrotungsten workshops Sintering chambers of sintering plants and primary mixing rooms Propylaea and other workshops in sintering plants

Roofs with breastplate Within

Out of

Frequent Quasi-permanent

value

value

value

coefficient

coefficient

coefficient

ψc

ψf

ψq

0.9

0.9

0.8

breastplates breastplates

0.5

0.75

0.30

-

0.75

0.30

0.75

1.00

0.30

0.30

0.50

0.30

0.50

1.00

0.20

0.30

-

-

1.00

-

-

0.50

-

-

Workshops with dust sources in cement mills ( kiln rooms, mill 7

rooms, combined storehouses, drying rooms and fragmentation rooms) Workshops without dust sources in

8

cement mills ( compressor plants, workshops, material sheds and distribution substations)

Note: 1. In the Table, the evenly distributed load of soot formation shall be only applicable to the roof slope α≤25°. If α≥45°, the dust load may be neglected. If 25°2.5H, z takes 2.5H;

Figure 7.2.2 Mountain Peak and Sidehill Schematic

For other positions of the mountain peak and sidehill, they may comply with figure 7.2.2, compensation factor at Part A, Part C (ηA and ηC) is 1, while the compensation factors between A and B or between B and C are determined by linear interpolation of η. 2 For the blocking terrains like intermontaine basin and valley, η=0.75~0.85; For the valley mouth and mountain pass concurrent with the wind direction, η=1.20~1.50. 7.2.3 For high seas offing and insular buildings or structures, the variation coefficient of the wind pressure height may not only be determined by roughness type of A-type on the basis of Table 7.2.1, but shall also consider the compensation factor shown in Table 7.2.3. Table 7.2.3 Compensation Factor η of High Seas Offing and Island Distance away from the coast (km)

η

4h, µs=0.6

15

Close-type gable roof with parapet When the parapet height is limited, the shape coefficient of the roof may be adopted as roof without parapet

16

Close-type gable roof with canopy

µs of the windward slope is adopted by Item 2.

Two opposite 17

close-type gable roof with canopy This Fig. is applicable to that with s of 8~20mm, and µs of windward slope is adopted by Item 2.

Close-type pitched 18

roof or arched roof with subsiding scuttle

26

Table 7.3.1 (Continued) Items

Type

Shapes and shape coefficient µs

Close-type gable roof 19

or arched roof with subsiding scuttle µs of the second scuttle surface of the windward is adopted by the following requirements: When a≤4h, µs=0.2 When a>4h, µs=0.6

20

Close-type roof with scuttle wind shield

Close-type double 21

span roof with scuttle wind shield

22

Close type saw-tooth roof µs of windward slope is adopted by Item 2. When the tooth surface increases or reduces, it may be regulated evenly in (1), (2) and (3) three sections.

Close-type 23

complicated multi-span roof µs of the scuttle surface is adopted by the following requirements: When a≤4h, µs=0.2 When a>4h, µs=0.6

27

Table 7.3.1 (Continued) Items

Type

Shapes and shape coefficient µs

This Fig. is applicable to conditions that shape coefficient µs in Hm/H≥2 and s/H = 0.2~0.4

Backing 24

close-type gable roof

Shape coefficient µs：

28

Table 7.3.1 (Continued) Items

Type

Shapes and shape coefficient µs

Backing 25

close-type gable roof

This Fig. is applicable to conditions that shape coefficient µs in Hm/H≥2and s/H =0.2~0.4;

with scuttle

Single-sided 26

open type gable roof

µs of the windward slope is adopted by Item 2.

29

Table 7.3.1 (Continued) Items

Type

Shapes and shape coefficient µs With

gable

Open

on

in

Shape coefficient µs

Double-side open 27

type and four-side open type gable roof The median is calculated by interpolation method Note: 1 Roof of this Fig. is allergic to wind, so to shall consider the sign reversal condition of µs when designing; 2 Overall horizontal force to the roof caused by longitudinal wind loads; When a≥30°, a is 0.05Aωh When a